First of all, I have seen some older threads but no solution.
I noticed that just today, happens on two different computers but both with Win 10. Not caused by the last build.
Could you please take a look at a simple empty app I created and report whether you have the problem too?
When I press Space, the pauses for like 1 or sometimes even 2 seconds, and then resumes. I can see that the memory goes up by 2 MB approximately and stays so. If you restart the app (F2), it does not happen, so it seems related to loading of some sound routines..?
EDIT: Interestingly, it works just fine when I use "Play sample file". So the problem is related to using "Play sample"..