It would be nice if portage would run the pkg_pretend phase in parallel jobs.
For example, when installing KDE/Plasma 5, every ebuild which inherits kde5.eclass runs the kde5_pkg_pretend function. This takes a few minutes to complete for around 60+ packages.
* build log should be combined with the pkg_pretend log (they are currently separate because the build dir is destroyed in between)
* parallel-fetch tasks should be started at the same time as pkg_pretend
The pkg_pretend phases run in a coroutine since bug 710432, so running them in parallel should not be much work.
The UI will look very close to the existing emerge --jobs UI.