Created attachment 579939 [details] ffspikes.jpg User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0) Gecko/20100101 Firefox/8.0 Build ID: 20111104165243 Steps to reproduce: I do ordinary continuous use of Firefox 8 (hour or more) that includes trivial things like opening tabs, reading sites, closing other tab (while opened tabs are between 4 and 20). Actual results: After 30 to 90 minutes of usage CPU lag spikes begin to appear that with time passing become bigger and bigger to the point that Firefox starts to freeze for a second every 5-10 seconds. At the beginning the spikes are only visible on Process Explorer graph. But later on become more and more noticeable by only using FF. I was able to track down that this is so only with Lastpass addon installed. Without Lastpass addon the spikes appear too but they remain only at their initial strength where don't affect FF but are only seen at Process Explorer graph. Its possible that they may become bigger but this would be much more slower 'cos I never been able to use FF without Lastpass loaded and get big spikes. I'm attaching jpg with Process Explorer lag spikes graph.
Just to add that no other applications are effected. By this i mean that other applications remain responsive despite cpu spikes and FF is the only one that freezes on cpu spikes.