Well the fi8rst observation I'd make is that you don't need that 98 performance indicator ( which you'll only get if your OS and CPU decide you need the CPU powered to max frequency, which they'll do if they detect a heavy workload ). When it drops down to 66 that's STILL a very good performance index for Pianoteq and it's extremely unlikely that Pianoteq would have any issues at that level of performance.
Polyphony of 139 is huge, more than you'd need in any real world situation IMO.
The sound crackles, CPU Frequency goes to 12000 to 33101, and Performance index drop to 66
Ignore the performance index drop - it's a non-issue. Even the lower level is still way more than you could need.
The CPU frequency drop is due to the power saving mode your CPU ( and most CPUs from Intel ) use. Even with this on your performance index, sample rate and polyphony are fine ( very high ), so again ignore this non-issue. People run Pianoteq quite happily on much less powerful CPUs.
The source of the crackles and pops might be due to that M-Audio 2x2 and it's drivers and/or cabling. Try running Pianoteq without that device and see if the pops and crackles go away. If the issue goes away look for updated drivers on the M-Audio website. When in doubt, remove hardware and see what happens is the general rule. You might try googling just "Windows 10 pops crackles" and see what you get - I'd always suspect Windows first and everything else later, honestly, and I think you'll find there are many people with that issue who use neither Pianoteq ( or the M-Audio 2x2 ).
If there's an issue with latency try raising sample buffer size ( in the devices tab of the options window of Pianoteq ). I think 64 is the lowest and you may be pushing your overall system into unrealistic levels. I've seen no data about typical settings for this, but it's worth trying and easy to undo.