I don't think that speed is the most important problem of intel drivers, but definitely stability with kde 4! I just began testing Debian wheezy and the intel gfx drivers are still unstable with kde 4.6. i even upgraded my test install to sid and got mesa/xserver-xorg-core(+depends) from exp. That means i even used xserver 1.12rc + mesa 8.0 to compare, but that did not fix the stability issues. Opengl kde effects often do not work, with squeeze + xorg bpo at least xrender usually worked, but now also xrender is impossible to use. xserver crashes while switching from window to fullscreen - looks like composite is VERY unstable with kde. at least vaapi worked in my short tests with h264,vc1 and mpeg2 full hd content via latest xbmc from git. the intel devs should be forced to use kde 4 for at least 1 month got get rid of those bugs... btw. i updated gl2benchmark to work with wheezy/sid/oneiric/precise (ubuntu with enabled universe repository):
It is a nice tool to verify rendering. The 4th test is usually rendered wrong with oss drivers (for every driver i tested), you can also use it to verify bugs with fglrx 11-12/12-1 and hd 5 series as well... But it should definitely not crash the xserver on close. I just don't know why the snapshot feature does not work.
printf 'deb http://kanotix.com/files/fix/gl2benchmark.wheezy ./\ndeb-src http://kanotix.com/files/fix/gl2benchmark.wheezy ./\n' > /etc/apt/sources.list.d/gl2benchmark.list
wget -qO- http://kanotix.com/files/fix/gl2benchmark.wheezy/Kanotix.gpg|apt-key add -
apt-get install --yes gl2benchmark