How to fix the video lag in Firefox!

Lately my video (HD) playbacks in YouTube seemed to be lagging a LOT! I wondered why. I thought it would be me and my years old OS or perhaps even somehow my pc.

But no it wasn’t. The lag was caused by Firefox’s session saving feature. A simple and fast change in it and “poof” went the lag.

• Open Firefox and type in “about:config” (without the “) in the Address Bar and hit Enter.
• Type in “session” in the “Filter” line at the top of the list.
• Find “browser.sessionstore.interval” and double click it. The 10000 milliseconds (equals 10 seconds) is the interval in which Firefox keeps saving your session in case of a crash; same amount of time between video lags.
• Change it to something different. 120000 equals 2 minutes, 300000 equals 5 minutes or something else you desire. I went with 600000 (10 minutes), because I don’t particularly care about session saving.