After a recent system upgrade, firefox became quite slow. The problem is especially noticable when opening, closing and switching between tabs. The actions are delayed for a second or more and xorgs cpu usage spikes to 100% during that time. After considering the relevant software updates, I could work around the problem, by reverting from x11-libs/cairo-1.12.14-r4 to x11-libs/cairo-1.10.2-r3. The other package versions are: firefox-17.0.9 xorg-server-1.14.3-r2 (previously 1.13.4) nvidia-drivers-304.108 gtk+-2.2.17 gentoo-sources-3.10.7-r1 (previously 3.8.13) Further checks show, that installing cairo with the legacy-drivers use-flag enabled fixes the problem as well. Without it cairo-1.12.14 and cairo-1.12.16 both show the problem. My graphic hardware consists of two nvidia geforce 7600gs with xinerama.
I don't see any issues at all with x11-drivers/nvidia-drivers-304.108 and a GeForce 6200.
With current versions (cairo-1.12.16 and nvidia-drivers-304.123), the problem seems to be gone. So I'll close this.
