If you are using IE – like I do most of the time – you may notice that occassionally the spinning cube in the header starts chugging horribly (and I mean horribly) when other SWFs are running on screen as well. (Edited: I ended up removing the SWF from the header – it was just causing too many headaches.)
I spent quite a bit of time trying to figure out what’s causing this, and I was just about ready to climb into a nearby bell-tower and start picking off people when I finally found an explanation.
The cube SWF is running with its wmode set to “opaque” (instead of the default “window”) to prevent it from rendering on top of other display-elements (e.g. the gallery pictures), and it turns out that this is triggering a buggy behavior in IE.
There’s a great demonstration of the phenomenon right here:
Ouch. What a bummer.