Some users may have noticed that YouTube videos can be slightly ‘jumpy’ in Firefox. Cain’t say I have or have not noticed this issue, may be I just thought it was normal. Anyway this problem started with Firefox 2 which introduced the Session Restore feature.

Many users, myself included, visit YouTube on an almost daily basis. Ever since Firefox version 2.0 implemented the session restore function, when you are watching a video on YouTube (perhaps on other video sites as well, I haven’t really tested that), you may notice a tiny freeze-up of the video every 10 seconds or so. This happens because the session restore is by default set to save all open tabs every 10 seconds. This is especially noticeable if you happen to have a lot of tabs open at once.

There is an easy fix for this involving changing a setting in your about:config

1. In a new tab type about:config in the address bar and press enter
2. In the filter field type browser.sessionstore.interval
3. Double-click on the entry
4. In the pop-up enter 120000 (tabs will be saved about 2-minutes) or 300000 (tabs will be saved about  5-minutes)
5. Click OK
6. Close the tab

By the way here’s another good Firefox/YouTube ‘Tweak’ YouTube: Auto Buffer and Stop AutoPlay

Source: Grand Stream Dreams