Not sure, but maybe this thread is related?
http://www.renoise.com/board/index.php?sho…c=21090&hl=
Yeah, do that:
- Make sure renoise is using 4 cores (not just one) under preferences.
- Post the log of your renoise session: Help => Show the Log File
- Wait a little.
Although it’s possible that 2.1 takes a little more CPU than 1.8, it definitely should not take that much more CPU so we definitely have some configuration issue on our hands.