Re: your glxgears fps is fast?
there are many potential reasons. Working 'cool'n'quit' - or its intel equivalent. Something in the background 'stealing' fps. Some other reasons.
Long story short: glxgears is only usefull if you compare absolutly identical setups where you changed just one thing (like different windowmanager in kde or gnome, or slightly different settings for your scheduler) and even then glxgears is not very usefull. There are a lot better ways to bench your system.