I frequently have these problems with flash block on. So that leaves HTML java script and java. java of corse displays a icon when it runs, so that leaves java script and HTML.
I still mantain that each tab shuld have its own thread so that if the tab is using to much resources the browser can halt it before it locks everything up to the point that even the cursor is slow when doing a end task on k meleon.
A multi-process architecture spawns multiple completely separate processes, with all of the overheads attached to each individual process.
Chrome's multi-process model is just an unnecessary ressource hog.
Multi-threading and multi-process plugins on the other hand would make sense.