>> Wich Classic, you can adjust cache size for each connection separately.

> How to do that? I've never seen this on documentation.

It is connection parameter. E.g.
in ISQL use "-cache <num>" command line switch,
in FSQL you can add "CACHE <num>" parameter to CONNECT command,
with FB API use isc_dpb_num_buffers parameter in isc_attach_database() call,
etc.

Ivan
http://www.volny.cz/iprenosil/interbase/