You wrote:
... This database is used only by me, there are no
triggers, procedures, indexes, not even a primary key. I empty it at the
beginning of the routine, and stuff it full again<g>.
...
---------------------

Emtpy it, and stuffing it? Does this smell of garbage collection activity?
After emptying the table, do a select count(*) from XXX. This might take
more time than you'd excpect.
Then, do the stuffing again. Any improvement in speed?

Regards,
Aage J.