I have been dealing with Helen on this issue and I produced a test
program with the same code (exact) from my production server code
and it does not show the same behavior as from my server code.
First a little background, I use IBO in a TCP/IP server, as each
user connects a thread is spawned to handle the socket.
In the constructor of each users thread object I create the IBO
session, connection, transaction and a cursor object.
When the server starts it reads a INI file and one of the settings
is to use the IBO connection pool. When the use pool flag is set
instead of doing a disconnect I do a disconnecttopool. Performance
when using the pool is very good, but it causes the FB server
process to rise until all connections in the pool are cleared.

I don't keep each threads connection connected all the time, because
it would not be a good Idea to have 1000 connections to the DB at
the same time as 1000 connections to the socket server, so I only
connect and disconnect when commands are recieved that use the DB.

Like I said before I created a Form based app that uses the same
blob code (EXACT) and I can send blob after blob after blob and the
FB server process stays around 23mb even if I upload a 15mb file.
When I do the exact same thing from my servers client thread I can
get the FB servers process to rise to 100mb in just a few minutes of
uploading 10mb files.

The only difference is that my test app is operating in the context
of a VCL main app thread while my server code is operating in a
tthread object.

So my question is this, Does the IBO connection pool have issues
with being used from a thread? Is it relying on some VCL feature
that is not availabe in a tthread, i.e. like the windows message
queue?
I have the full source but I have not had time to dig deep into it
and see what the issue is.

So I hope maybe Jason has some ideas which may help.

Thanks