Firefox slower with nVidia drivers

Hi,
I am using OpenSuse 11.0 32 bits with KDE 3.x. I upgraded the latest version of the nVidia drivers (i own a nVidia 8600M GM). I have been testing that with the nVidia drivers switching the windows tabs in Firefox is slower than without the driver.
Does anybody have the same problem? Anybody knows how to solve it?
Thanks