Quote Originally Posted by cseeman View Post
It would seem that it's system related.
I assume this is only impacting the interface and not the stream. That might indicate some background task but it's hard to figure out what.

Some things to look at are RAM, available vs use of VRAM. Sometimes other applications don't let go of RAM or lots of VRAM is used when the drive is low on space resulting in slow access. One can see this to some extent looking at RAM use at the bottom of Activity Monitor where the total system stats are displayed.
Correct, Stream is not impacted, not dropping frames, just the interface.

Just upgraded the Macbook to 8GB of RAM, Activity Monitor says 4GB used / 4 Free

Only other apps opened are TTFN Midi and MidiPipe for Korg Nano Controller. Nothing else running in the background.