Do you have your printer turned on while your surfing? I see it listed in your System Details.

Anything which adds to Firefox, or any other browser for that matter will slow it down and consume CPU cycles.

Try running FF in Diagnose Firefox issues using Troubleshoot Mode If it runs efficiently, then one or more of your add-ons is the culprit.

Also, run the Plugins check I noticed a couple which were out of date and which could expose your system to attack.

Thanks.

yes, my printers are on, they are always on. why would having my printers on cause FF to work at 40% CPU or use 700 megs of memory? it doesn't make sense, and if that is the case, then FF isn't built properly, and that's disappointing.

re the plugins - i have no updates to download, according to FF.

Update.

it seems a little better - the memory is down at the moment to 225MB.

the CPU usage seems to be around 10%, but does go up to 30% on its own (ie - without any change in my usage - no new tabs etc..).

Modern CPUs can run at up to 65% without influencing performance so I wouldn't be too concerned about half that figure.

As regards printers, Windows maps any hardware to memory so that it's always available more or less immediately.

I'm surprised you get a clean bill of health with your plugins check though. Shockwave needs updating and your Java is out of date. You can update the latter via Windows Control Panel. Download Shockwave from here: http://get.adobe.com/shockwave/