Hi @dbpro - If you haven't tried this, I would take note of the audio interface settings in S1 2.5.6 and make sure they are configured the same in your S1 3 install. It sounds like the S1 3 install is configured for a very small buffer. Also - take note of your CPU utilization. Some more things to try to get a better understanding of what's going on after verifying the same audio configuration between the two installed versions and your CPU usage is calm with an empty song is to:
- create a test song and try loading a single test audio track and press play
- if that plays properly, add a few plugins
- if that plays properly, try loading a previous small project that played properly in S1 2
If this doesn't give illuminating results, come back and let us know how these tests went.