I am running v3.0.22 with CAT tracking and the IF set for an External Radio (panadapter on 1st IF).

SDR is an SDRPlay RSP1A.

For me it slows down a bit when I tune with the radio dial but doesn't stall anything like yours. I suspect the issue is either the latency issue jdow described or a PC performance issue.

What is your CPU doing during this time? Is one of the SDR Console threads maxing out a core?