steps I tried and emerge --info

firefox_42_0-r1_still_crashes_on_exit_with_hardened-sources-4_2_6_getting_4_2_6-r1.log (text/plain), 32.57 KB, created by abandoned account disabled email on 2015-11-14 04:37:41 UTC

//no logs here but I've tested 42.0-r1 with -system-cairo and -egl  and with system-cairo and -egl
//the difference between egl and -egl seems to be that the latter allows hardware acceleration(for me, at least) to work in firefox! so I kept it at: -egl
//system-cairo with hardware acceleration set in Preferences (I'll call it: hwaccel) has 8-9fps, and without hwaccel has 5fps.
//-system-cairo with hwaccel has 5fps(if I remember right) and without has 16fps (yes! better without! and huge difference)
//tested all those with the working(for me) kernel hardened 4.2.5-r1
//Also tested with both system-cairo and -system-cairo with kernel 4.2.6 the issue that I reported in comment #2 is still happening for me. But no crashes on new tabs, as reported by OP in comment #0
//Since comment #2 I've even disabled network keep-alive and ipv6 in about:config (to no effect: still works on 4.2.5-r1, still doesn't on 4.2.6)
//UPDATE: If I stay for a few more minutes, looks like those "Waiting for website.here.com..." do finish and things are working(youtube videos load and play, comments show, sites in other tabs are loading, eventually!) So, they don't hang forever... they just take way longer ... ! AND, looks like once it gets past this delay once, then any new/other tabs load normally(fast). So, I'm thinking it might be something that I'm blocking that firefox insists, perhaps, on waiting until it loads or times out, before allowing any other network connections to finish. BUT, it must be something with kernel 4.2.6, because it works fine with 4.2.5-r1 ... so odd. (will test 4.2.6-r1 below, at the end). It also does not crash on exit. (Issue went away completely with 4.2.6-r1)
//I'm including about:support to see all my about:config flag changes.
this is about:support

Application Basics
------------------

Name: Firefox
Version: 42.0
Build ID: 20151113235155
User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:42.0) Gecko/20100101 Firefox/42.0
Multiprocess Windows: 0/1 (default: false)
Safe Mode: false

Extensions
----------

Name: Calomel SSL Validation
Version: 0.78
Enabled: true
ID: [e-mail]

Name: Certificate Patrol
Version: 2.0.14.1-signed
Enabled: true
ID: [e-mail]

Name: Disable Ctrl-Q Shortcut
Version: 20131016
Enabled: true
ID: [e-mail]

Name: HTTPS-Everywhere
Version: 5.1.1
Enabled: true
ID: [e-mail]

Name: NoScript
Version: 2.6.9.37
Enabled: true
ID: {73a6fe31-595d-460b-a920-fcc0f8843232}

Name: RefControl
Version: 0.8.17.1-signed
Enabled: true
ID: {455D905A-D37C-4643-A9E2-F6FEFAA0424A}

Name: RightToClick
Version: 2.9.5.1-signed
Enabled: true
ID: {cd617375-6743-4ee8-bac4-fbf10f35729e}

Name: Tree Style Tab
Version: 0.15.20150902901
Enabled: true
ID: [e-mail]

Name: uBlock Origin
Version: 1.3.4
Enabled: true
ID: [e-mail]

Name: uMatrix
Version: 0.9.3.1
Enabled: true
ID: [e-mail]

Name: Firebug
Version: 2.0.12
Enabled: false
ID: [e-mail]

Name: FireStorage Plus!
Version: 1.7
Enabled: false
ID: [e-mail]

Graphics
--------

Adapter Description: X.Org -- Gallium 0.4 on AMD SUMO (DRM 2.43.0, LLVM 3.8.0)
Asynchronous Pan/Zoom: none
Device ID: Gallium 0.4 on AMD SUMO (DRM 2.43.0, LLVM 3.8.0)
Driver Version: 2.1 Mesa 11.0.4
GPU Accelerated Windows: 1/1 OpenGL (OMTC)
Supports Hardware H264 Decoding: false
Vendor ID: X.Org
windowLayerManagerRemote: true
AzureCanvasBackend: cairo
AzureContentBackend: cairo
AzureFallbackCanvasBackend: none
AzureSkiaAccelerated: 0
CairoUseXRender: 1

Important Modified Preferences
------------------------------

accessibility.blockautorefresh: true
accessibility.typeaheadfind: false
accessibility.typeaheadfind.flashBar: 0
browser.cache.disk.capacity: 3145728
browser.cache.disk.filesystem_reported: 1
browser.cache.disk.max_entry_size: 1151200
browser.cache.disk.parent_directory: /tmp/firefoxcache/
browser.cache.disk.smart_size.enabled: false
browser.cache.disk.smart_size.first_run: false
browser.cache.disk.smart_size.use_old_max: false
browser.cache.frecency_experiment: 2
browser.cache.memory.capacity: 5131072
browser.cache.memory.max_entry_size: 125120
browser.download.importedFromSqlite: true
browser.newtab.url: about:blank
browser.places.smartBookmarksVersion: 7
browser.search.update: false
browser.search.update.log: true
browser.sessionstore.upgradeBackup.latestBuildID: 20151113235155
browser.startup.homepage: about:blank
browser.startup.homepage_override.buildID: 20151113235155
browser.startup.homepage_override.mstone: 42.0
browser.tabs.insertRelatedAfterCurrent: false
browser.tabs.insertRelatedAfterCurrent.backup: true
dom.apps.reset-permissions: true
dom.event.clipboardevents.enabled: false
dom.mozApps.used: true
extensions.lastAppVersion: 42.0
font.name.serif.x-western: monospace
layers.async-pan-zoom.enabled: true
media.gmp-gmpopenh264.enabled: false
media.gmp-manager.buildID: 20151113235155
media.peerconnection.default_iceservers:
media.peerconnection.enabled: false
media.peerconnection.ice.default_address_only: true
media.peerconnection.identity.enabled: false
media.peerconnection.turn.disable: true
media.peerconnection.use_document_iceservers: false
media.peerconnection.video.enabled: false
mousewheel.with_shift.action: 1
network.cookie.cookieBehavior: 1
network.cookie.prefsMigrated: true
network.dns.disableIPv6: true
network.dns.disablePrefetch: true
network.dns.disablePrefetchFromHTTPS: true
network.http.keep-alive.timeout: 0
network.http.referer.XOriginPolicy: 1
network.http.sendSecureXSiteReferrer: false
network.http.speculative-parallel-limit: 0
network.predictor.cleaned-up: true
network.prefetch-next: false
network.tcp.keepalive.enabled: false
places.database.lastMaintenance: 1447150212
places.history.expiration.transient_current_max_pages: 104858
plugin.disable_full_page_plugin_for_types: application/pdf
plugins.notifyMissingFlash: false
privacy.cpd.offlineApps: true
privacy.cpd.siteSettings: true
privacy.sanitize.migrateFx3Prefs: true
privacy.sanitize.timeSpan: 0
security.enable_ssl3: false
security.enable_tls: true
security.OCSP.enabled: 0
security.ssl3.dhe_dss_aes_128_sha: true
security.ssl3.dhe_dss_aes_256_sha: true
security.ssl3.dhe_dss_camellia_128_sha: true
security.ssl3.dhe_dss_camellia_256_sha: true
security.ssl3.dhe_dss_des_ede3_sha: false
security.ssl3.dhe_rsa_camellia_128_sha: true
security.ssl3.dhe_rsa_camellia_256_sha: true
security.ssl3.dhe_rsa_des_ede3_sha: false
security.ssl3.ecdh_ecdsa_aes_128_sha: true
security.ssl3.ecdh_ecdsa_aes_256_sha: true
security.ssl3.ecdh_ecdsa_des_ede3_sha: false
security.ssl3.ecdh_ecdsa_rc4_128_sha: false
security.ssl3.ecdh_rsa_aes_128_sha: true
security.ssl3.ecdh_rsa_aes_256_sha: true
security.ssl3.ecdh_rsa_des_ede3_sha: false
security.ssl3.ecdh_rsa_rc4_128_sha: false
security.ssl3.ecdhe_ecdsa_des_ede3_sha: false
security.ssl3.ecdhe_ecdsa_rc4_128_sha: false
security.ssl3.ecdhe_rsa_des_ede3_sha: false
security.ssl3.ecdhe_rsa_rc4_128_sha: false
security.ssl3.rsa_camellia_128_sha: true
security.ssl3.rsa_camellia_256_sha: true
security.ssl3.rsa_des_ede3_sha: false
security.ssl3.rsa_fips_des_ede3_sha: false
security.ssl3.rsa_rc4_128_md5: false
security.ssl3.rsa_rc4_128_sha: false
security.ssl3.rsa_seed_sha: false
security.tls.insecure_fallback_hosts.use_static_list: false
security.tls.unrestricted_rc4_fallback: false
security.tls.version.min: 2
storage.vacuum.last.index: 1
storage.vacuum.last.places.sqlite: 1446462900
webgl.disabled: true

Important Locked Preferences
----------------------------

JavaScript
----------

Incremental GC: true

Accessibility
-------------

Activated: false
Prevent Accessibility: 0

Library Versions
----------------

NSPR
Expected minimum version: 4.10.10
Version in use: 4.10.10

NSS
Expected minimum version: 3.20.1 Basic ECC
Version in use: 3.20.1 Basic ECC

NSSSMIME
Expected minimum version: 3.20.1 Basic ECC
Version in use: 3.20.1 Basic ECC

NSSSSL
Expected minimum version: 3.20.1 Basic ECC
Version in use: 3.20.1 Basic ECC

NSSUTIL
Expected minimum version: 3.20.1
Version in use: 3.20.1

Experimental Features
---------------------

Sandbox
-------

Seccomp-BPF (System Call Filtering): true
Seccomp Thread Synchronization: true
User Namespaces for privileged processes: true
User Namespaces: false
Media Plugin Sandboxing: true


//this(/that ^) is firefox 42.0-r1 with hardened-sources-4.2.6 as follows (-egl and system-cairo):
$ cd /tmp; time firefox

(firefox:9453): GLib-GObject-WARNING **: The property GtkSettings:gtk-menu-images is deprecated and shouldn't be used anymore. It will be removed in a future version.

(firefox:9453): GLib-GObject-WARNING **: The property GtkSettings:gtk-button-images is deprecated and shouldn't be used anymore. It will be removed in a future version.
ATTENTION: default value of option force_s3tc_enable overridden by environment.
Can't find symbol 'glXCreateContextAttribsARB'.

(firefox:9453): GLib-GObject-WARNING **: The property GtkSettings:gtk-menu-images is deprecated and shouldn't be used anymore. It will be removed in a future version.

(firefox:9453): GLib-GObject-WARNING **: The property GtkSettings:gtk-button-images is deprecated and shouldn't be used anymore. It will be removed in a future version.
ATTENTION: default value of option force_s3tc_enable overridden by environment.
Can't find symbol 'glXCreateContextAttribsARB'.
*** BUG ***
In pixman_region32_fini: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug

TSTBrowser::restoreTree
  level = 1
  tabsToRestore = 20
  restoring member tabs = 20 (0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19)
*** BUG ***
In pixman_region32_fini: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_region32_fini: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_region32_reset: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_region32_fini: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_region32_fini: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_region32_fini: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_region32_fini: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_region32_reset: Malformed region region
Set a breakpoint on '_pixman_log_error' to debug


Segmentation fault (core dumped)

real  2m7.018s
user  1m6.393s
sys 1m15.153s
//That core dump happens only when exiting firefox, not on new tab creation; however any new tabs do not load (stuck on "Waiting for website.here.com...") and even though the initially focused tab on firefox startup does load, apparently, it won't really load if it's a youtube video(video is blank, while it's Waiting for something.googlevideo.com...) nor can you log in to bgo for example. It only does all this with kernel hardened-sources-4.2.6  but not with hardened-sources-4.2.5-r1 !
//(tested later on: If I keep only the first focused tab even though it was a youtube video which didn't load because of this issue and even though I opened a new window with the same url that also didn't load, exiting firefox didn't crash dump. Either crashes happen only sometimes, or the prerequisite for them is  having to open or try to load(one of the restored-on-startup-but-were-never-focused tabs) at least one other tab)

$ emerge --info firefox x11-libs/cairo

Portage 2.2.24 (python 3.4.3-final-0, hardened/linux/amd64/no-multilib, gcc-5.2.0, glibc-2.22-r1, 4.2.6-hardened x86_64)
=================================================================
                         System Settings
=================================================================
System uname: Linux-4.2.6-hardened-x86_64-AMD_A6-3400M_APU_with_Radeon-tm-_HD_Graphics-with-gentoo-2.2
KiB Mem:    15872120 total,  13291844 free
KiB Swap:   33554428 total,  33554428 free
Timestamp of repository gentoo: Fri, 13 Nov 2015 00:45:01 +0000
sh bash 4.3_p42
ld GNU ld (Gentoo 2.25.1 p1.1) 2.25.1
ccache version 3.2.4 [enabled]
app-shells/bash:          4.3_p42::gentoo
dev-lang/perl:            5.22.0::gentoo
dev-lang/python:          2.7.10-r2::gentoo, 3.4.3-r2::gentoo
dev-util/ccache:          3.2.4::gentoo
dev-util/cmake:           3.3.2-r1::gentoo
dev-util/pkgconfig:       0.29::gentoo
sys-apps/baselayout:      2.2::gentoo
sys-apps/openrc:          0.18.3::gentoo
sys-apps/sandbox:         2.9::gentoo
sys-devel/autoconf:       2.13::gentoo, 2.69-r1::gentoo
sys-devel/automake:       1.11.6-r1::gentoo, 1.13.4::gentoo, 1.14.1::gentoo, 1.15::gentoo
sys-devel/binutils:       2.25.1-r1::gentoo
sys-devel/gcc:            5.2.0::gentoo
sys-devel/gcc-config:     1.8::gentoo
sys-devel/libtool:        2.4.6-r1::gentoo
sys-devel/make:           4.1-r1::gentoo
sys-kernel/linux-headers: 4.3::gentoo (virtual/os-headers)
sys-libs/glibc:           2.22-r1::gentoo
Repositories:

gentoo
    location: /usr/portage
    priority: -1000

mozilla
    location: /var/lib/layman/mozilla
    masters: gentoo
    priority: 50

tox-overlay
    location: /var/lib/layman/tox-overlay
    masters: gentoo
    priority: 50

ACCEPT_KEYWORDS="amd64 ~amd64"
ACCEPT_LICENSE="@FREE"
CBUILD="x86_64-pc-linux-gnu"
CFLAGS="-O2 -pipe -march=native -ggdb -fvar-tracking-assignments -fno-omit-frame-pointer -ftrack-macro-expansion=2 -fstack-protector-all -fPIC"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/lib64/libreoffice/program/sofficerc /usr/share/gnupg/qualified.txt"
CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo"
CXXFLAGS="-O2 -pipe -march=native -ggdb -fvar-tracking-assignments -fno-omit-frame-pointer -ftrack-macro-expansion=2 -fstack-protector-all -fPIC"
DISTDIR="/usr/portage/distfiles"
FCFLAGS="-O2 -pipe"
FEATURES="assume-digests binpkg-logs binpkg-multi-instance ccache cgroup collision-protect config-protect-if-modified distlocks downgrade-backup ebuild-locks fakeroot fixlafiles force-mirror installsources ipc-sandbox merge-sync multilib-strict network-sandbox news nostrip parallel-fetch parallel-install prelink-checksums preserve-libs sandbox sfperms split-elog split-log strict unknown-features-warn unmerge-backup unmerge-logs userfetch userpriv usersandbox webrsync-gpg"
FFLAGS="-O2 -pipe"
GENTOO_MIRRORS="http://de-mirror.org/gentoo/ http://gd.tuwien.ac.at/opsys/linux/gentoo/ http://ftp.romnet.org/gentoo/ http://tux.rainside.sk/gentoo/  http://www.las.ic.unicamp.br/pub/gentoo/"
INSTALL_MASK="/lib/systemd /lib32/systemd /lib64/systemd /usr/lib/systemd /usr/lib32/systemd /usr/lib64/systemd /etc/systemd"
LANG="en_US.utf8"
LDFLAGS="-Wl,-O1 -Wl,--as-needed"
MAKEOPTS="-j4"
PKGDIR="/usr/portage/packages"
PORTAGE_CONFIGROOT="/"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages"
PORTAGE_TMPDIR="/var/tmp"
USE="3dnow 3dnowext X acl amd64 berkdb bindist btrfs bzip2 cli consolekit cracklib crypt cryptsetup cscope cxx dbus device-mapper dri egl extensions gdbm git gpg gpm gtk3 hardened iconv jpeg justify lm_sensors lock mmx mmxext modules mosh-hardening ncurses nptl ogg openmp opus pam pax_kernel pcre pie png policykit popcnt pulseaudio qt4 readline seccomp session smp sse sse2 sse3 sse4a ssl ssp startup-notification strong-security system-icu system-jpeg system-libvpx system-sqlite urandom xattr xcomposite xtpax zlib" ABI_X86="64" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="kexi words flow plan sheets stage tables krita karbon braindump author" CAMERAS="ptp2" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="3dnow 3dnowext mmx mmxext popcnt sse sse2 sse3 sse4a" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ublox ubx" GRUB_PLATFORMS="pc" INPUT_DEVICES="keyboard synaptics evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php5-5" PYTHON_SINGLE_TARGET="python2_7" PYTHON_TARGETS="python2_7 python3_4" RUBY_TARGETS="ruby20 ruby21" USERLAND="GNU" VIDEO_CARDS="radeon" XFCE_PLUGINS="brightness clock trash battery power" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account"
USE_PYTHON="2.7"
Unset:  CC, CPPFLAGS, CTARGET, CXX, EMERGE_DEFAULT_OPTS, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS

=================================================================
                        Package Settings
=================================================================

www-client/firefox-42.0-r1::mozilla was built with the following:
USE="bindist dbus gstreamer gtk3 hardened jemalloc3 pulseaudio startup-notification system-cairo system-icu system-jpeg system-libvpx system-sqlite -custom-cflags -custom-optimization -debug -egl (-gmp-autoupdate) -gstreamer-0 -jit -minimal (-neon) (-pgo) (-selinux) -test -wifi" LINGUAS="-af -ar -as -ast -be -bg -bn_BD -bn_IN -br -bs -ca -cs -cy -da -de -el -en_GB -en_ZA -eo -es_AR -es_CL -es_ES -es_MX -et -eu -fa -fi -fr -fy_NL -ga_IE -gd -gl -gu_IN -he -hi_IN -hr -hu -hy_AM -id -is -it -ja -kk -km -kn -ko -lt -lv -mai -mk -ml -mr -nb_NO -nl -nn_NO -or -pa_IN -pl -pt_BR -pt_PT -rm -ro -ru -si -sk -sl -son -sq -sr -sv_SE -ta -te -th -tr -uk -vi -xh -zh_CN -zh_TW"
CFLAGS="-pipe -march=native -ggdb -fno-omit-frame-pointer -fstack-protector-all -fPIC"
CXXFLAGS="-pipe -march=native -ggdb -fno-omit-frame-pointer -fstack-protector-all -fPIC"
LDFLAGS="-Wl,-O1 -Wl,--as-needed -Wl,-z,relro,-z,now"


x11-libs/cairo-1.14.4::gentoo was built with the following:
USE="X glib opengl svg xcb (-aqua) -debug (-directfb) (-gles2) -static-libs -valgrind -xlib-xcb"

$ equery m nspr
!!! Package dev-libs/nspr-4.10.10 is missing metadata.xml

$ equery w nspr
/var/lib/layman/mozilla/dev-libs/nspr/nspr-4.10.10.ebuild

$ la /var/lib/layman/mozilla/dev-libs/nspr/
total 8
drwxr-xr-x 1 root root   64 13.11.2015 21:47 ./
drwxr-xr-x 1 root root   30 13.11.2015 21:47 ../
drwxr-xr-x 1 root root  416 13.11.2015 21:47 files/
-rw-r--r-- 1 root root  380 13.11.2015 21:47 Manifest
-rw-r--r-- 1 root root 4064 13.11.2015 21:47 nspr-4.10.10.ebuild

$ time coredump_to_backtrace `which firefox` /tmp/core all >~/logs/firefox42_0-r1_crash_on_exit_backtrace_full_7.log 2>&1

real  1m7.193s
user  0m55.657s
sys 0m5.877s


# layman -S

 * Fetching remote list...
 * Fetch Ok

 * Syncing selected overlay(s)...
 * Running Git... # ( cd /var/lib/layman/mozilla  && /usr/bin/git pull )
Already up-to-date.
 * Running Git... # ( cd /var/lib/layman/tox-overlay  && /usr/bin/git pull )
Already up-to-date.
 * 
 * Succeeded:
 * ------
 * Successfully synchronized overlay "mozilla".
 * Successfully synchronized overlay "tox-overlay".
 * 

# time emerge --verbose --tree --update --deep --with-bdeps=y --changed-use --ask @world --exclude "libreoffice libreoffice-l10n"

These are the packages that would be merged, in reverse order:

Calculating dependencies... done!

Total: 0 packages, Size of downloads: 0 KiB

Nothing to merge; quitting.


real	1m5.897s
user	0m58.580s
sys	0m4.577s

$ uname -a
Linux gobaby 4.2.6-hardened #4 SMP Thu Nov 12 12:51:55 CET 2015 x86_64 AMD A6-3400M APU with Radeon(tm) HD Graphics AuthenticAMD GNU/Linux

the .config for 4.2.5-hardened-r2 (which works fine) and 4.2.6-hardened is the same, except for:
-CONFIG_LOCALVERSION="-g45b4b78"
+CONFIG_LOCALVERSION=""

# time emerge-webrsync -v -k
...
//this downloaded new and updated
...
real	2m25.613s
user	0m56.533s
sys	1m15.777s

# time emerge --verbose --tree --update --deep --with-bdeps=y --changed-use --ask @world --exclude "libreoffice libreoffice-l10n"

These are the packages that would be merged, in reverse order:

Calculating dependencies... done!
[ebuild     U  ] media-video/mplayer-1.2-r2::gentoo [1.2-r1::gentoo] USE="X cdio dvd dvdnav enca encode iconv jpeg libass osdmenu png pulseaudio shm truetype xscreensaver xv -a52 -aalib -alsa (-altivec) (-aqua) -bidi -bl -bluray -bs2b -cddb -cdparanoia -cpudetection -debug -dga -directfb -doc -dts -dv -dvb -faac -faad -fbcon -ftp -ggi -gif -gsm -ipv6 -jack -joystick -jpeg2k -ladspa -libcaca -libmpeg2 -lirc -live -lzo -mad -md5sum -mng -mp3 -nas -network -nut -openal -opengl -oss -pnm -pvr -radio -rar -rtc -rtmp -samba -sdl (-selinux) -speex -tga -theora -toolame -tremor -twolame -unicode -v4l -vdpau (-vidix) -vorbis -x264 -xanim -xinerama -xvid -xvmc -zoran" CPU_FLAGS_X86="3dnow 3dnowext mmx mmxext sse sse2 -ssse3" VIDEO_CARDS="-mga -s3virge -tdfx" 0 KiB
[ebuild  NS    ] sys-kernel/hardened-sources-4.2.6-r1:4.2.6-r1::gentoo [4.1.6:4.1.6::gentoo, 4.1.7-r1:4.1.7-r1::gentoo, 4.2.3:4.2.3::gentoo, 4.2.3-r1:4.2.3-r1::gentoo, 4.2.3-r2:4.2.3-r2::gentoo, 4.2.3-r3:4.2.3-r3::gentoo, 4.2.3-r4:4.2.3-r4::gentoo, 4.2.3-r5:4.2.3-r5::gentoo, 4.2.4:4.2.4::gentoo, 4.2.4-r2:4.2.4-r2::gentoo, 4.2.5:4.2.5::gentoo, 4.2.5-r1:4.2.5-r1::gentoo, 4.2.5-r2:4.2.5-r2::gentoo, 4.2.6:4.2.6::gentoo] USE="-build -deblob -symlink" 1,606 KiB
[ebuild     U  ] dev-python/lxml-3.5.0::gentoo [3.4.4::gentoo] USE="threads -doc -examples {-test}" PYTHON_TARGETS="python2_7 python3_4 -python3_3 -python3_5%" 3,721 KiB
[ebuild     U  ] dev-util/cmake-3.4.0::gentoo [3.3.2-r1::gentoo] USE="ncurses qt4 -doc -emacs -qt5 -system-jsoncpp {-test}" 6,563 KiB
[nomerge       ] media-video/mplayer-1.2-r2::gentoo [1.2-r1::gentoo] USE="X cdio dvd dvdnav enca encode iconv jpeg libass osdmenu png pulseaudio shm truetype xscreensaver xv -a52 -aalib -alsa (-altivec) (-aqua) -bidi -bl -bluray -bs2b -cddb -cdparanoia -cpudetection -debug -dga -directfb -doc -dts -dv -dvb -faac -faad -fbcon -ftp -ggi -gif -gsm -ipv6 -jack -joystick -jpeg2k -ladspa -libcaca -libmpeg2 -lirc -live -lzo -mad -md5sum -mng -mp3 -nas -network -nut -openal -opengl -oss -pnm -pvr -radio -rar -rtc -rtmp -samba -sdl (-selinux) -speex -tga -theora -toolame -tremor -twolame -unicode -v4l -vdpau (-vidix) -vorbis -x264 -xanim -xinerama -xvid -xvmc -zoran" CPU_FLAGS_X86="3dnow 3dnowext mmx mmxext sse sse2 -ssse3" VIDEO_CARDS="-mga -s3virge -tdfx" 
[ebuild  N     ]  dev-libs/libcdio-paranoia-0.93_p1::gentoo  USE="cxx -static-libs {-test}" 670 KiB
[ebuild  N     ]   app-eselect/eselect-cdparanoia-0.1::gentoo  0 KiB
[ebuild     U  ] sys-apps/busybox-1.24.1::gentoo [1.23.2::gentoo] USE="-debug -ipv6 -livecd -make-symlinks -math -mdev -pam* -savedconfig (-selinux) -sep-usr -static -syslog -systemd" 2,021 KiB

Total: 7 packages (4 upgrades, 2 new, 1 in new slot), Size of downloads: 14,579 KiB

Would you like to merge these packages? [Yes/No] 
>>> Verifying ebuild manifests

!!! Digest verification failed:
!!! /usr/portage/sys-apps/busybox/busybox-9999.ebuild
!!! Reason: Filesize does not match recorded size
!!! Got: 8493
!!! Expected: 8580

real	1m24.621s
user	0m56.403s
sys	0m2.727s

//whell...

# sed -e 's/ 8580 / 8493 /'  -i /usr/portage/sys-apps/busybox/Manifest

# time emerge --verbose --tree --update --deep --with-bdeps=y --changed-use --ask @world --exclude "libreoffice libreoffice-l10n"
...
Total: 7 packages (4 upgrades, 2 new, 1 in new slot), Size of downloads: 14,579 KiB

Would you like to merge these packages? [Yes/No]
>>> Verifying ebuild manifests

!!! Digest verification failed:
!!! /usr/portage/sys-apps/busybox/busybox-1.24.1.ebuild
!!! Reason: Filesize does not match recorded size
!!! Got: 8577
!!! Expected: 8579

real	1m6.469s
user	0m56.117s
sys	0m2.270s

//How do I regen only the filesize? not the hash too.
# cd /usr/portage/sys-apps/busybox/
# cp Manifest metadata.xml /tmp
# repoman -pv  --digest=n  --ask manifest[INFO] checking package sys-apps/busybox

!!! Digest verification failed:
!!! /usr/portage/sys-apps/busybox/busybox-1.24.1.ebuild
!!! Reason: Filesize does not match recorded size
!!! Got: 8577
!!! Expected: 8579
!!! sorry, xmllint is needed.  failing
# e-file xmllint
[I] dev-libs/libxml2
	Available Versions:	2.8.0-r2 2.9.1-r1 2.7.7 2.9.1-r5 2.9.1-r4 2.9.2 2.9.2-r1001 2.9.0-r2 2.9.2-r1 2.9.2-r4 2.9.2-r3 2.8.0-r1 
	Last Installed Ver:	2.9.2-r4(Wed 11 Nov 2015 04:12:08 AM CET)
	Homepage:		http://www.xmlsoft.org/
	Description:		Version 2 of the library to manipulate XML files
	Matched Files:		/usr/bin/xmllint; 

 *  dev-embedded/scratchbox-devkit-doctools
	Available Versions:	1.0.14 
	Homepage:		http://www.scratchbox.org/
	Description:		A cross-compilation toolkit designed to make embedded Linux application development easier
	Matched Files:		/opt/scratchbox/devkits/doctools/bin/xmllint; 

 *  app-shells/bash-completion
	Available Versions:	2.1-r2 2.1_p20141224 1.2 2.1 1.1-r5 1.3-r2 
	Homepage:		http://bash-completion.alioth.debian.org/
	Description:		Programmable Completion for bash
	Matched Files:		/usr/share/bash-completion/completions/xmllint; /usr/share/bash-completion/xmllint; 

# xmllint --version
xmllint: using libxml version 20902
   compiled with: Threads Tree Output Push Reader Patterns Writer SAXv1 FTP HTTP DTDValid HTML Legacy C14N Catalog XPath XPointer XInclude Iconv ISO8859X Unicode Regexps Automata Expr Schemas Schematron Modules Debug Zlib 

# repoman -pv  --digest=y  --ask manifest
[INFO] checking package sys-apps/busybox

!!! Digest verification failed:
!!! /usr/portage/sys-apps/busybox/busybox-9999.ebuild
!!! Reason: Failed on SHA256 verification
!!! Got: c63a8a1e692e3db32065b7b6ea8a295815e7f18a8bc8d61467b317d2ba3ad8ce
!!! Expected: 7aff319a88b045355843b9c4b565d207b686fbb3823773c84dc03eef41769e40
!!! sorry, xmllint is needed.  failing

//Oh wait I forgot that -p got fixed! and the error message with -p is confusing like that! FIXME: ?

# repoman -v  --digest=n  --ask manifest
[INFO] checking package sys-apps/busybox
>>> Creating Manifest for /usr/portage/sys-apps/busybox

# colordiff -up /tmp/metadata.xml metadata.xml
//nothing

# colordiff /tmp/Manifest Manifest 
47,48c47,48
< EBUILD busybox-1.24.1.ebuild 8579 SHA256 da4928a32451934c578e9c350f612b1e25e8d41c75efe06591139f2b54132a91 SHA512 13558fd2e840dbbb379ef13f41665fb424b366081aeb3fdd4849271f3d574ff828c5ecd88a7e60932c0cbebf95fa4214d98ba76935bbdbe815d4c7643bec60ec WHIRLPOOL f2658665fcec5b431f931695d68dc780f0fb7c2ea73694d680fd791ebeb8d04fdcd787528537bfaa43ece36fb6bcaa7157d3f5973893e7c6185bbfbe63bbc0a5
< EBUILD busybox-9999.ebuild 8493 SHA256 7aff319a88b045355843b9c4b565d207b686fbb3823773c84dc03eef41769e40 SHA512 d9136ebeec4270a6413da2e82f6c42a04bb7450704b2a500c0ef1ca54d9a571628c1f568ba6c5682c6a8a01779bfb5cb77c1d110675fb6253e187b695707163f WHIRLPOOL e72b404b3c13bf1bb4ad5a272cd92c410936c4c2bf69dd953164c23d8902ea513a49324e626340878602285ebe156dbd36c4b22faf142ff48ee4fdecf009b56f
---
> EBUILD busybox-1.24.1.ebuild 8577 SHA256 31eaac028521cc6bd5f2b1e65cbc49a46d1e1bb1de5a0bcb52e5f110380ce66d SHA512 2809dd31ddfbe8f4f296d3959b7ac1ac752a0ddb08c31546e531e2e5e557bf5fc42488472514cf8ab0e62314d18e2e3f09c4af08894a4dee2ccd7221beabee92 WHIRLPOOL 66ce51fafea5b8d73e7ef0044f6c235ffc01aa6047f6ff336b09f6e1d6dff2ff2e13140bd324c1566d5b74fefe5448745c7fde38e9a319cf0c4cbee986175305
> EBUILD busybox-9999.ebuild 8493 SHA256 c63a8a1e692e3db32065b7b6ea8a295815e7f18a8bc8d61467b317d2ba3ad8ce SHA512 62b247c12bfaea62418fbe3f7a6c12f127f24083f00c5ed0e3cf89d04397557a54cfbb8e527d66cf688c33e0689515bd69b94c86768b797d7e14594f45a947f7 WHIRLPOOL 95424edd37ebeea691bc5f62dffafbec5d2545790768f1861c4ad2ce6f25931c44e33c4a6903d2afab3b8a6dfcf3b9e5c9a865bfe197bf98361254b82181f635

//Well sheesh, I guess it was very silly of me to expect the size to be different but not the hash! (what was I thinking?!)
//So, was the manifest not updated for busybox 1.24.1 and git versions? or something changed the files without rebuilding manifest (same thing right?)
//I'll skip installing it, until next webrsync I guess

# time emerge-webrsync -v -kFetching most recent snapshot ...
 * Latest snapshot date: 20151113
...
# rm /usr/portage/metadata/timestamp.x
# time emerge-webrsync -v -k
...
real	1m21.579s
user	0m52.597s
sys	0m38.537s

# time emerge --verbose --tree --update --deep --with-bdeps=y --changed-use --ask @world --exclude "libreoffice libreoffice-l10n busybox"

These are the packages that would be merged, in reverse order:

Calculating dependencies... done!
[ebuild     U  ] media-video/mplayer-1.2-r2::gentoo [1.2-r1::gentoo] USE="X cdio dvd dvdnav enca encode iconv jpeg libass osdmenu png pulseaudio shm truetype xscreensaver xv -a52 -aalib -alsa (-altivec) (-aqua) -bidi -bl -bluray -bs2b -cddb -cdparanoia -cpudetection -debug -dga -directfb -doc -dts -dv -dvb -faac -faad -fbcon -ftp -ggi -gif -gsm -ipv6 -jack -joystick -jpeg2k -ladspa -libcaca -libmpeg2 -lirc -live -lzo -mad -md5sum -mng -mp3 -nas -network -nut -openal -opengl -oss -pnm -pvr -radio -rar -rtc -rtmp -samba -sdl (-selinux) -speex -tga -theora -toolame -tremor -twolame -unicode -v4l -vdpau (-vidix) -vorbis -x264 -xanim -xinerama -xvid -xvmc -zoran" CPU_FLAGS_X86="3dnow 3dnowext mmx mmxext sse sse2 -ssse3" VIDEO_CARDS="-mga -s3virge -tdfx" 0 KiB
[ebuild     U  ] dev-python/lxml-3.5.0::gentoo [3.4.4::gentoo] USE="threads -doc -examples {-test}" PYTHON_TARGETS="python2_7 python3_4 -python3_3 -python3_5%" 3,721 KiB
[ebuild  NS    ] sys-kernel/hardened-sources-4.2.6-r1:4.2.6-r1::gentoo [4.1.6:4.1.6::gentoo, 4.1.7-r1:4.1.7-r1::gentoo, 4.2.3:4.2.3::gentoo, 4.2.3-r1:4.2.3-r1::gentoo, 4.2.3-r2:4.2.3-r2::gentoo, 4.2.3-r3:4.2.3-r3::gentoo, 4.2.3-r4:4.2.3-r4::gentoo, 4.2.3-r5:4.2.3-r5::gentoo, 4.2.4:4.2.4::gentoo, 4.2.4-r2:4.2.4-r2::gentoo, 4.2.5:4.2.5::gentoo, 4.2.5-r1:4.2.5-r1::gentoo, 4.2.5-r2:4.2.5-r2::gentoo, 4.2.6:4.2.6::gentoo] USE="-build -deblob -symlink" 1,606 KiB
[ebuild     U  ] dev-util/cmake-3.4.0::gentoo [3.3.2-r1::gentoo] USE="ncurses qt4 -doc -emacs -qt5 -system-jsoncpp {-test}" 6,563 KiB
[nomerge       ] media-video/mplayer-1.2-r2::gentoo [1.2-r1::gentoo] USE="X cdio dvd dvdnav enca encode iconv jpeg libass osdmenu png pulseaudio shm truetype xscreensaver xv -a52 -aalib -alsa (-altivec) (-aqua) -bidi -bl -bluray -bs2b -cddb -cdparanoia -cpudetection -debug -dga -directfb -doc -dts -dv -dvb -faac -faad -fbcon -ftp -ggi -gif -gsm -ipv6 -jack -joystick -jpeg2k -ladspa -libcaca -libmpeg2 -lirc -live -lzo -mad -md5sum -mng -mp3 -nas -network -nut -openal -opengl -oss -pnm -pvr -radio -rar -rtc -rtmp -samba -sdl (-selinux) -speex -tga -theora -toolame -tremor -twolame -unicode -v4l -vdpau (-vidix) -vorbis -x264 -xanim -xinerama -xvid -xvmc -zoran" CPU_FLAGS_X86="3dnow 3dnowext mmx mmxext sse sse2 -ssse3" VIDEO_CARDS="-mga -s3virge -tdfx" 
[ebuild  N     ]  dev-libs/libcdio-paranoia-0.93_p1::gentoo  USE="cxx -static-libs {-test}" 670 KiB
[ebuild  N     ]   app-eselect/eselect-cdparanoia-0.1::gentoo  0 KiB

Total: 6 packages (3 upgrades, 2 new, 1 in new slot), Size of downloads: 12,559 KiB

Would you like to merge these packages? [Yes/No] 
...
...
...
real	34m10.269s
user	53m22.610s
sys	12m13.887s


# cd /usr/src/
# cp --interactive -- linux/.config linux-4.2.6-hardened-r1/
# eselect kernel list
Available kernel symlink targets:
  [1]   linux-4.1.6-hardened
  [2]   linux-4.1.7-hardened-r1
  [3]   linux-4.2.3-hardened
  [4]   linux-4.2.3-hardened-r1
  [5]   linux-4.2.3-hardened-r2
  [6]   linux-4.2.3-hardened-r3
  [7]   linux-4.2.3-hardened-r4
  [8]   linux-4.2.3-hardened-r5
  [9]   linux-4.2.4-hardened
  [10]  linux-4.2.4-hardened-r2
  [11]  linux-4.2.5-hardened
  [12]  linux-4.2.5-hardened-r1
  [13]  linux-4.2.5-hardened-r2
  [14]  linux-4.2.6-hardened *
  [15]  linux-4.2.6-hardened-r1
# eselect kernel set 15
-----------
root@gobaby 2015/11/14 04:49:23 -su4.3.42 t:3 j:0 d:1 pp:15828 p:15849
!5939 5 0  4.2.6-hardened #4 SMP Thu Nov 12 12:51:55 CET 2015
/usr/src
/usr/src # eselect kernel show
Current kernel symlink:
  /usr/src/linux-4.2.6-hardened-r1

# logout
$ regenkernel 
...
real	27m19.204s
user	56m25.213s
sys	8m59.490s
//+about 2 mins

//rebooting...

//Well, the issue is totally fixed in 4.2.6-r1 ! 
//retesting fps: 5fps without hwaccel, 9fps with hwaccel! (remember this is with: system-cairo and -egl)
//used this to test fps: https://developer.mozilla.org/media/uploads/demos/p/a/paulrouget/8bfba7f0b6c62d877a2b82dd5e10931e/hacksmozillaorg-achi_1334270447_demo_package/HWACCEL/