I got crackles when recording MIDI to audio in Vista and 10 but not XP nor 7. I fixed it in 10 by bringing the screen resolution down.
So you reduced the processing load. Good trick.
Koz
I came to it by chance. I reinstalled 10 for other reasons and ran it at its default resolution for my system, which is lower than my chosen 1278 x 1024.
A trick to hand onto others with the same problem?