Thank you.

The graphics-generating threads are already assigned "Low Priority", and I'm unsure how to look for a bottleneck. I already know that the system behaves quite differently in 'release' mode from in 'debug' mode because the thread synchronisation is all completely different - one of the threads is receiving images over an ethernet connection, so can't easily be 'slowed down'.

I have a support subscription, so this may be one to ask them about...

Stephen.