User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0 Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0 Hi, I downloaded and installed FF4 yesterday afternoon and was happy because it was indeed faster than 3.6 for running javascript(ogame.dk). Today it has slowed down and I checked my task manager, realizing that FF4 consumed 50% CPU and about 2GB memory(using only 4 tabs)! After a restart of FF4 it is down to 167mb memory I experienced a memory leak in 3.6 as well but that was no where near this one :/ (using as much as 10 tabs FF3.6 used up to 300mb memory before I restarted it) I have no idea wether this memory leak is in the script engine or in firefox in generel, ogame.dk is using heavy javascript but the other 3 tabs are not. Reproducible: Didn't try

Likely an addon, could you see if the issue occurs with a new, empty testing profile? (Don't install any addons into it yet) http://support.mozilla.com/kb/Basic+Troubleshooting#w_8-make-a-new-profile If that works fine, could you try enabling/disabling addons in your existing profile and seeing what makes a difference - thanks!

Well actually I haven't been able to reproduce it. As we speak FF4 uses about 275mb with the following add-ons: GreaseMonkey(4 script installed), Adblock Plus, danish and english dictionary, Download Statusbar, Firebug, FoxyTunes, GalaxyToolbar, GWT Developer Plugin, Java console(btw. how can I remove old ones? I have like 6, 5 of which are deactivated) and several plugins like Foxit PDF reader, Shockwave, MS Office, Google Talk, Java, MediaPlayer and Silverlight. Maybe it was just a glitch :) I have also created a clean profile and will try to use it if I experience the problem again. Until then it might be okay to close this bug unless someone else has the same problem.

Works fine for me on Mozilla/5.0 (Windows NT 6.1; rv:2.0) Gecko/20100101 Firefox/4.0