Firebird + php + Delphi -> php slow down

Hello,

I have a problem:

I wrote Delphi a database application client that has a permanent connection to the Firebird database while it is running. It uses IBX.

There is a php site that uses the same Firebird database. The php pages only connect to the Firebird database when data is selected or modified, they do not have permanent connection.

The users use the Delphi clients and the php site at the same time. In this case the php site slows down very much, exactly the firebird calls from php are very slow.

When there is no Delphi client running and only the php site is used by the users the php site is fast.

Why does the php site slow down when Delphi clients are using the firebird database as well with permanent connections?

Thanks,
Istvan