Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
you can try disable your addons and enable it one by one, see if its a problem with a specific addon.
 
Nope, I haven't had a single problem with the new Firefox yet - it runs great on all operating systems.
 
I've had nothing but trouble with Firefox since installing it on my Mac (I used it on Windows for years). Both version 3 and 3.5 take about 5 minutes to open (usually after crashing 4-5 times). No other program crashes like this. Safari is fine though, fast and has never crashed... Confused.
 
restarting it tends to help but its gets sluggish fairly quick

Are you running add ons? Have you tried a complete clean reinstall and trashing your profile and starting again?

Try a clean install of 3.5 and DO NOT install ANY add-ons. Run the browser like that for a while and keep monitoring performance and see how well it runs.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.