I've had this problem for some time and it's driving me insane. What happens is that Firefox 5 will scroll really slow and sometimes even lag jump down the scrollbar. On top of that sometimes the sites will just lag while loading or scrolling in general. I've tried all sorts of setups to get this to work right. I just don't know what to do anymore. I'm getting to the point where I just may switch back to windows (which I really REALLY don't want to do). I originally thought it was a situation with flash but it doesn't seem to be the case. Therefore, there must be something else that is causing this.
This site in particular causes massive lag on my end with scrolling:
I have a feeling the problem with the scrolling has to be the Nvidia Proprietary driver. The reason I say this is because it works fine when using a live CD or when the system is on the Nouveau driver. I've tried disabling hardware acceleration, messing with compiz, reinstalling flash, and several other methods described on the web (lets just say I've been researching and at this problem for weeks). I've finally given up and I'm going to ask for help. Hopefully I get an answer here or elsewhere to this problem. :)
The scrolling problem may be tied to the fact that, sometimes randomly it will cause my system to halt (freeze) completely and I have to restart the system. The mouse is frozen and the system is unresponsive. Again, I have a feeling it has to do with the nVidia drivers. I want to point out that Chrome scrolls perfectly and has no issues (though I don't particularly like chrome and I shouldn't have to be forced to use it.) The system did flip out once with flash on chrome but not sure if that was just a random incident.
I'm desperate for a fix for this as I'm a recent convert to Linux. I absolutely love the system and I find it fun to use. Though this slight situation with something as simple as a browser is cutting into my patience.
Here is a link to my system specs (well not all of it obviously): http://xruptor.tripod.com/
Ubuntu 11.04 (64-bit), Nvidia driver (275.19)