I have a library installed called kwinnvidiahack4, googling at what is does only showed some old stuff, is it still needed? I tried with export KWIN_NVIDIA_HACK=o and 1 and could not see any obvious difference (kwin appears slow and jerky in both instances (with kde4.5rc3) although frame rates are pretty high (88-100fps)

$ kwin(29525) KWin::CompositingPrefs::detectDriverAndVersion: GL vendor is "NVIDIA Corporation"
kwin(29525) KWin::CompositingPrefs::detectDriverAndVersion: GL renderer is "GeForce 6600 GT/AGP/SSE2"
kwin(29525) KWin::CompositingPrefs::detectDriverAndVersion: GL version is "2.1.2 NVIDIA 256.35"
kwin(29525) KWin::CompositingPrefs::detectDriverAndVersion: Detected driver "nvidia" , version "256.35"

I don't have such a lib in openSuse and all references I could find Google'ing for it refer to Mandriva, so you might wish to post on their forum. Maybe it's a distro specific hack?

no it just might be that their packages are split differently

To quote the source file for the nvidia hack:
"The only purpose of this file is to be later in the link order than
(nvidia's) libGL, thus being initialized by the dynamic linker before it,
allowing it to set __GL_YIELD=NOTHING soon enough for libGL to notice it."

So yes, I would say it is still required.

I didn't understand a word if that except that I still need it