interesting ideas about dropstuff, I was more thinking of for example other apps like Word eating CPU time even if you only read a document... or if it's in background... (where the priority discussion comes in)

cheers

There's no such thing as "background" and "foreground" any more. All applications run at the whim of the system scheduler without regard for which one you (the user) happen to be interacting with at any given instant.

(There are some exceptions. Virtual PC 5 tries to set its CPU usage differently depending on whether or not it's the active application. I don't think that feature actually works.)

Word eats up CPU time because you have background spell-checking and pagination turned on. Turn them off, and your problem will largely go away. Not completely, because Word as a Carbon (and poorly Carbonized, at that) application still uses the old event polling scheme, which means it constantly has to run a little loop rather than waiting for dispatches from the OS. But that's not that big a deal.

An even better suggestion is to use TextEdit instead of Word. It's faster, smaller, and comes with your computer for free.

hehe, I don't use Word. I was just using it as an example of bad software. With background, I exactly meant what you explained ;-)
cheers