hi: this problem been going on for at least 3 months so it is cross version of Firefox as I've updated recently to 17. after a while, I think it's 1.5-2hr if I've been surfing .. doing stuff on MacBook.. andcfirefox been open entire time I hear the CPU do a surge and stay at it this higher CPU. last night I worked out it was purely Firefox. I closed Firefox down and within 1-2min.. CPU was back to normal. no heavy sound of processing my MacBook Pro is only 1 year old. so it's app issue not hardware. last night I retested this three times first time / only Firefox open second time / Firefox and Opera third time / Firefox / opera and mail all three times when closed Firefox CPU went back to normal. tonight I will turn off all addons to double check they are not cause. I think I've did that and still CPU usage surge. but will double check to be absolutely sure. --- Firefox I use extensively I have 1 one window with 15 tabs for stuff I'm researching and currently working on each tab is simple site eg amazon book page 2 another window with my ACTION tabs. typically 4-5 open --- "so my question is" 1 what is suggested troubleshoot steps to work out which part of the Firefox solution is causing my CPU usage 2 what are common things to check with CPU surges? thankyou in advance