John,

<< Unfortunately this is causing the app to go quite slow.  If I add a
process running on a timer which called flushbuffers for all tables (there
are only 5 affected) in a different session does this flush the data for all
the other session's tables? >>

Only if the tables are all being opened within the same process.  If there
are separate processes involved, then no, they are only flushed on a
per-process basis.

The basic design is that all table files are opened once, and only once, per
engine instance, and the engine is instantiated once per process instance.

--
Tim Young
Elevate Software
www.elevatesoft.com