perhaps this is because firefox requires a bigger memory footprint when it starts so it can multithread? firefox probably assigns a thread to grabbing the page, one to filtering content and one to parse the page. on my computer, when viewing the reply page here, firefox is using 145mb of virtual memory (ram + swap space) and the cpu usage is at 2% (amd semperon 2400+ - 1.6gHz - single core). out of a total of 512mb of ram and it still leaves me plenty of cpu time, ram and swap space to run all of this: never over 30% cpu usage for all that. i can still play a graphics/cpu intensive linux game even with no problems. never a single problem with firefox, only thing on my computer that has ever leaked memory is gaim. perhaps windows is your problem?