User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0 (Beta/Release) Build ID: 20140314220517 Steps to reproduce: 1. create new firefox profile. 2. start firefox. 3. turn on option "smooth scrolling". 4. load any web page. 5. scroll page vertically. use arrow buttons on keyboard. vertical scrolling is jerky (not smooth). 6. open new tab, for example pressing ctrl+t. after that you can close this tab. 7. switch back to the first tab. scroll page vertically. now vertical scrolling is smooth! 8. wait for 5 minutes (may be less). 9. scroll page vertically. vertical scrolling is jerky again. :( 10. repeat steps 6-10. Configuration: Windows 7 x64 with Aero. CPU 4 cores. "Use hardware acceleration when available" doesn't affect this bug.

hey, is there anybody alive? firefox 29 also have jerky scrolling.

I found reason of this bug: Windows system clock resolution. Clockres.exe shows current clock resolution (http://technet.microsoft.com/en-us/sysinternals/bb897568.aspx). Standard resolution on 99% computers ~15 ms. With this resolution, scrolling is jerky. With resolution ~1 ms, scrolling is smooth. 'Opening tab' animation (see step 6 in my first post) temporarily increases resolution from 15 ms to 1ms. I don't want to set resolution permanently to 1 ms because this reduces overall system performance and eats battery. Better way: this bug must be fixed. :) Web site to test vertical scroll: http://habrahabr.ru/

I also have this bug for a long time. At first scrolling is very jerky, but after I open and close new tab or turn on autoscrolling for a moment, scrolling become smooth. I've tried also beta, aurora and nightly but problem occurs on every version. My configuration: i5 3360-M with HD4000 graphics only OS: Windows 8.1 x64

I made Greasemonkey script that fix this bug for me. https://greasyfork.org/scripts/3508-fix-firefox-smooth-scrolling But this is just temporary and dirty hack.

Thanks, it's working for me also.

Another interesting information. Smoothness very sensitive to monitor's vertical refresh rate. With 1920x1080@64, instead of "standard" 60 Hz (or 59 Hz HDMI), scrolling almost smooth. With 1 ms system clock resolution, 60 Hz is more smooth than 64 Hz.

This bug is very noticeable in FF40 on Win10 and a G3258 chip. CoolCmd's Greasemonkey script is still an effective fix, and cost to system performance (CPU % usage) during scrolling seems to be negligible.