I'm using (Arch) Linux, and my system is completely up to date (that includes all graphics drivers etc). In firefox it's like whenever the screen updates it's a few ms delayed. When scrolling it doesn't really scroll instantly (I have disabled smooth scrolling), whenever I type something the text doesn't instantly show up. It's not a huge delay, just a fraction of a second. It's big enough to be noticable though. This does not happen in google chrome, chromium or opera. I have disabled hardware acceleration and restarted FF, it seems to have helped to speed up text appearing when I type. These problems have been here since I first installed FF. I'm willing to try anything as it seems that Firefox is the only browser which doesn't give me artifacts and freeze up my monitors (it seems that Chromium/Chrome and Opera causes X to completely hang, which means I have to reboot to be able to do anything).