Firefox using lots of processor?

[gumbald]

Even as I type this I get the odd stutter as I see the processor graph shoot up every now and then... Started a couple of days ago, occasionally get the beach ball when changing between tabs and had to wait a good few minutes last night while Facebook home loaded.

Anyone else had anything similar recently? How can I try and track down what's causing it? Latest Firefox and running 10.5.6 on a 2008 iMac.

 

[gumbald]

You have AdBlock Plus, NoScript or Foxmarks? They're my only addons.

EDIT: There's 3.0.10, I didn't have this! I'll see if this calms it down.