In the last few days I have noticed that whenever I visit a post topic the CPU usage suddenly goes up from 1%-5% to nearly 100%. In activity monitor the process is shown as "safari web content". This doesn't happen when viewing a forum or when creating a topic (e.g. right now it's fine), but as soon as I read a post, the insane CPU usage begins. As soon as I close the window, the CPU usage drops to normal.
My system specs: Mac OS X 10.8.5, Safari 6.2.3