Thanks very much for the suggestions.

I gather that no one has experienced the same thing I am seeing.

I just tried all the suggestions.
Device manager was already set to do caching.
Emptied TIF (temporary internet files) and the Temp folder.
I used Disk Cleanup to do this, and checked to make sure it did it.
Emptied Recycle bin.

This didn't seem to make any difference. Still takes about 15
seconds.

BTW, when I start the save process, I can see the Excel statusbar
which says "Saving myaddin.xla." The progress indicator is visible,
but doesn't show any progress until the very end when it very quickly
runs through the entire length of the progress bar.

I have uninstalled and reinstalled office 2003, but this made no
difference.

I wonder what the heck it could be?