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You might have noticed that Firefox performs poorly when you surf for a long time or open lots of tabs at once. Many wrongly believe that this is due to some memory leak caused by extensions (even, I used to believe this). This is actually caused because Firefox stores 50 most recently visited websites in a memory session inorder to speed up the pageload of the previously visited site.
Average web surfer tend to visit only 3 – 5 websites out of the previously visited websites, so you can reduce the resource hog by changing the memory threshold to 5 (or anything below 50). This can be done by typing ‘about:config’ in your Firefox address bar and search for ‘browser.sessionhistory.max_entries’ (without quotes), right click on that entry and choose modify. Now set the value for 5 (or anything lower than 50).
I first read this trick on Ghack and then I tried it myself. It made my Firefox work smoothly for longer.
Via Jayaprakash
Written by 
wrote, on February 26th, 2007
Thanks for the Tricks thilak
wrote, on February 26th, 2007
Nice trick.
wrote, on February 26th, 2007
I have given it a shot. We will see what happens. I am assuming you have to restart Firefox for this to take place?
wrote, on February 27th, 2007
One way I speeded up my firefox is by disabling the searching for updates at beginning. this really increased my start up speed.
There are some other sweet firefox hacks.
wrote, on February 27th, 2007
gr8 trick….but i suggest this thing can also be done by
go to tools>Clear private data ,and check the appropriate boxes.
wrote, on February 27th, 2007
Good info, if I am not wrong even the guys from This Week In Tech said that the problems were coming from memory leaks. I will try this tweak.
wrote, on February 27th, 2007
Bryan: yup, I guess you’ll have to restart Firefox for the changes to reflect.
Anirudh: We will be glad if you share them with us
Abhishek: But, that will remove everything, including my saved password, history and cache files.
wrote, on February 27th, 2007
It Really worked for me Thilak.Nice Trick