I have a 27" i7 3.4Ghz 2011 iMac. When I am on Kijiji and zoom in on the web page (via both fingers moving away from each other horizontally) I notice it would stutter horribly when I scroll up and down. Horribly so. Tried it again on Macrumors forums and other forums and it does not exhibit stuttering at all. It seems as if it's software related, as no way that the beefy CPU could not manage such a simple task. Any ideas guys? Something to do with settings in Safari? Thanks.