> The basics of my application are as follows.
>
> - I'm using FB Embedded 2.0
> - A TCP Server receives a connection, creates a new thread and
> connects
> to the DB via the Embedded Engine
> - Each thread makes it's own connection to the database.

You must serialise isc_attach_database calls by some mutex or
critical section. As long as each thread operate within its own
attachment you don't need to synchronise other API calls

> - The system validates information, starting a transaction, executing
> 10 -> 15 selects and commiting the transaction. As stated the
> system executes ONLY SELECTS
> - All queries run against a single table with approx 35k rows.
> - Five columns in the table are used to form the WHERE clause and
> indexes have been created on those fields as required by the
> SELECTS
> - The result is then transmitted back to the client via TCP
>
> When processing requests for a SINGLE thread the AVG time per request
> is 7ms. If I increase the number of requesting applications and thus
> threads connected to the database to 200. The AVG time per request
> goes to 1400ms. So it appears that somewhere something is locking the
> entire database and not allowing other threads read access. :(

It seems your application have some problems with threads...

Regards,
Vlad