I love Firefox, and haven't really been drawn to the dark side of Chrome and Safari, but why does it sometimes cause my Mac's fan to race ?

Whilst I'm travelling so much with my job, I find the Mac more convenient for my travels, rather than carting my larger ( and more capable in terms of disk, RAM, Ubuntu etc. ) Thinkpad W500 around.

One thing that has recently started to bug me is that, from time to time, I can hear the Mac's fan start to race, implying that things are suddenly hotting up inside.

I started monitoring the fan using an open-source application called Fan Control whenever I heard it kick into life.

This morning, the same thing occurred, and Fan Control showed the temperature rising up past 70 degrees C, whereas it normally sits around 52-53 degrees C.

Apart from Notes, Symphony, Skype, Stickies and Lotus Mobile Connect ( my VPN client ), the only other thing I had open was Firefox 4.

I had a few tabs open to Twitter, Connections (W3), Connections (Greenhouse), Blogger etc. but wasn't doing anything that manic ....

As a test, I hit [CMD] [Q] to quit Firefox, and the fan noise AND temperature immediately started to drop.

Now I'm not blaming Firefox but ....

In the meantime, I'll keep my Firefox addiction stoked, with Plenty O' Plugins to keep me amused. To be honest, it's more likely that one of the plugins is causing the problem so I can't blame FF :-) 

Or can I ?