> I've a multi-threaded socket server which handles one client per thread
> and inserts data into a Firebird 2.0.3 database.
>
> I want to use the JayBird built-in connection pooling facility by using
> org.firebirdsql.pool.FBWrappingDataSource. When doing this, CPU
> utilization of my socket server application constantly stays on 50%
> after the first connection has been obtained from the pool.
> ...
> Any ideas what I'm doing wrong?

Short answer - no.

Long answer would be to use some profiling software and check where the
most time is spent in. One issue might be that for some reason your user
name, password, database path, etc is not correctly configured and pool
gets exception while trying to get a connection. In this case it will
retry and retry and retry... Other extreme part is that your 50% time
are simply needed for your normal work.

Roman