> Hope to get some feedback.

Do you connect and disconnect with every call? If so you are
probably running into a TIME_WAIT issue. Google for "netstat TIME_WAIT".
Try your test again either using the local xnet connection or keep
each of your threads connected rather than connect/disconnect every
time. To do this change your connection string from
localhost:Drive:\path\DB.fdb
to
Drive:\path\DB.fdb

hope this helps.
Regards,
Will.

--
http://www.cohesis.co.uk