Os X 10.6.5 update: half the framerate with anti-aliasing?

Since updating to OS X 10.6.5, enabling anti-aliasing by using
window.setGlutDisplayString(“rgba double samples>=4”)
leads to the framerate dropping significantly. With 60fps selected, it actually runs at only 30fps. There seem to be changes to opengl drivers in 10.6.5, so something probably needs adapting.