I just checked the MacBook Pro and Firefox was up to 5+ GB of RAM. Lots of beachball activity even though there was still ~ 7 GB of RAM free. FF was eating all the CPU too - to the point that "about:memory" wouldn't run ("non-responsive script").

That got me thinking that maybe it's a hard drive issue. Disk Utility said the drive is fine (the original 500 GB 5400 rpm Seagate). I repaired the Permissions, and as usual it found hundreds of things that were "wrong" and fixed them, but who knows if it has anything to do with anything.

Macs are great when they run fine, but they're inscrutable when something goes wrong.

Grr...

I hope you have better luck. It looks like at least some of the 2009 MacPros can handle 48 GB of RAM. http://www.everymac....index-macpro.html

Cheers,
Scott.

I cleaned out all the caches, cookies, saved sessions, etc., in FF before the running Disk Utility. I haven't zapped the PRAM yet - thanks for the reminder about that. If it still acts up, that'll be next on the list.

So far, it seems happy. About 480 MB of RAM used by FF for 6 tabs, but it usually takes a day or more for it to go nuts...

Thanks.

Cheers,
Scott.

I think I've zapped a PRAM about twice in my life. I haven't kept up with this stuff... Ya got me. :-)

I doubt that browser extensions are the issue. It's running less than I normally run - e.g. TabMixPlus, AdblockPlus, FlashBlock are about the only ones that have been installed (other than the usuals).

It's still happy at the moment - still only 480 MB of RAM used.

My guess is that there was some old garbage in the FF cache that was getting reloaded and grabbing memory and not freeing it properly. Yes, FF does have memory leaks, but this was really extreme.

I'm not willing to stick my neck out and say it's fixed, but it's looking good so far.

Thanks.

Cheers,
Scott.

Apparently it's still used, but likely not an issue in my case.

http://support.apple.com/kb/HT1379

HTH.

Cheers,
Scott.