Good morning everyone, I have problem with video display jumpiness every second when watching video on youtube (or others). I tried to follow many solutions recommend on internet but nothings work for me. Most of them said it caused by "implemented the session restore function". So I did the following : - change setting in "browser.sessionstore.interval" via about:config to 1500000 (old value = 15000) - clear all caches, clear history, restart firefox ( > but the problem still occurs), restart my computer. - disable "browser.sessionstore.resume_from_crash" to false. It's no work! Playing video on youtube is still lagging every second. (But audio work fine.) This annoying problem has temporarily happened when I opened many tabs ~ 15tabs or more and restored since the last closed. But I just fixed it by closing them, and restart my computer. The problem is gone, but not this time. I tried everyting I cound. I have no idea how to do next. Could you all please suggest what should I do to fix this? Thank you very much in advance for your help. REF: lifehacker.com/5342636/how-to-fix-annoying-youtube-jumpiness-in-firefox http://www.tomsguide.com/answers/id-2533860/youtube-videos-freezes.html