No slightly different results with Calculate VFX on GPU off. Tests were done with it on as well as within the export settings Hardware acceleration was applied where it could be.
Results for Calculate VFX on GPU switched off.
Exporting MP4
and exporting HEVC
and then
Finally turning off all GPU acceleration during export.
Won't be doing that test again as the CPU temperature climbed I stopped the export when the CPU got to 67c.