In this case, you basically have an outdated PC.  A P4 system only has one processor so it will have to go through the raw thumbs one at a time.  In handling raws one at a time, it will take that P4 CPU a dozen seconds or more on raws from some of the more recent cameras so that is going to be the major tie-up, not disk access.  On a quad core system, all four CPU's will be processing thumbs at the same time.  It's like having 4 registers open at checkout in the store instead of one.  Plus, every CPU on that quad core system will probably be about 2x as fast as your 2.26 GHZ P4 anyway.  That means that today's "average" quad core system is going to be about 8x faster than your P4 at building thumbs (and printing) in Qimage.

Now, Qimage will not re-cache your thumbs just because you installed a new version.  I think you are misjudging what is happening.  Either that or you didn't let the thumbs/cache build completely the last time you exited so it still has stuff to do when you revisit the folder.  When you go to a folder, it always says "building thumbs" and then "building raw cache".  If all are already built, you see the two appear very quickly but no countdown because it discovers they are already built.  On a local drive, that probably happens so fast you can't even see it.  On a NAS drive, you may see the words appear but nothing is actually being done (except for it checking to see IF they are built).

Mike