Noel, thanks for your detailed response to my questions.

I have BIAB 2018.

I've tried everything suggested but no change. The CPU is maxing out at 100% when trying to play a song with Real instruments. If I load a MIDI style it works fine.

The brighter side of this is the justification to buy a new computer. I'm not sure whether to get a notebook or desktop PC, but it's fun looking at what's available.