> I see. Perhaps it's something like this. How about if I have several
> connections : will these read pages be kept in memory for all of them?

Interbase maintains one cache per database, not per connection. So yes,
other connections would benefit from cached data of other connections. It
would be quite an oversight if they didnt.

> Unfortunately, I actually have all these indices, as well as quite a few
> others. :-(
> Besides, if it were an index problem, it would be systematic wouldn't it?

10 seconds is very long for such a small table with correct indexes, so I
suspect that perhaps a non relevant index is being used in the plan. This
could be the case if you have indexes on either num_fact or affretement
fields, or if the index selectivity is not correct - when is the last time
you did a full backup and restore?

Post the plan generated by IB Planalyzer for that query to gain some extra
insight.

BTW. Have you considered upgrading your server to firebird 1.5? Its much
faster than IB6.0.

Regards
Gary