Description of problem: Firefox's UI is very slow on my machine - moving mouse swiftly over menu items or speed dial causes the focus to lag greatly behind the cursor, sometimes not being re-drawn until the cursor stops. Version-Release number of selected component (if applicable): 27.0.1-1, but it has been happening in older versions too. How reproducible: On my machine (AMD Phenom X4 840 3.2 GHz, nVidia GTS 450), in Fedora, everytime. This happens in my XFCE and Openbox installations, and in XFCE and Gnome run from Live DVD (I did not seek further). I used both Nouveau and binary drivers, to no avail. However, the problem is not present in Linux Mint installed on the very same machine, so this must be a Fedora thing. Just as well, this problem is not present on Intel-based machines available to me (Intel Celeron 1.6 GHz + Intel 940 GML, Intel Core 2 Quad 3.4 GHz + nVidia Quadro). Steps to Reproduce: 1. Run Firefox in Fedora (installed or LiveCD) 2. Hover mouse over menus quickly Actual results: Focus lags greatly Expected results: Focus is redrawn immediately Additional info: I have tried disabling HW acceleration and/or smooth scrolling without results, and since the problem appears in fresh LiveCD installation too, I believe it is not cache-related.
Additional info #2: Attempt to reproduce the bug with Live DVD on AMD A4-5300 with integrated GPU yielded somewhat similar results - initially, the symptoms didn't show (e. g. the focus was redrawn normally), but after a few minutes, the slowness is the same, if not worse. In this case, only the open-source GPU drivers were used, and heavy graphics artifacts were present throughout the system (Gnome).
Correction: The slowness on the A4 was experienced only using SW rendering. HW rendering retained the timely focus update, but produced the artifacts.
Seems to be caused by your graphics pipeline. Do you see that with other apps? Can you test some gfx benchmarks, like glxgears or so?
No, I don't get that with anything but Firefox (and Seamonkey, as it turns out). Furthermore, I get the slowness with HW acceleration turned both on and off. I can't access the machine today, so I will run the tests as soon as possible. Anyway, with both open and closed sets of drivers, I recall getting glxgears results in high thousands (I am able to render 1080p video in mplayer through gl and gl2 comfortably). I will keep the needinfo box ticked until I'm able to run the tests.
Okay, I have run the glxgears. 21500 FPS on average.
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