Test in 2.21 Beta 56.
https://forums.highrez.co.uk/viewtopic.php?t=4968&sid=9d5018379ea65f839f45d5f4aa5c0eba
So I ran in performance profiler and did find some issues - non that make this noticable on my machine, but plenty than can be improved. Particually in the thread lock code which is not as efficient as it could be.