AME 13.0.2 (2019) Slowing Down after 2-3 hours

System:

iMac Pro 3Ghz Xeon, 64GB RAM, Vega 64

10.13.6 (High Sierra)

External Drive: QNAP TVS 1282T3 (Thunderbolt 3, 1GB/sec sustained)

Encoding ProresHQ -> ProresHQ, 486p content.  Using Neat Video Reduce Noise, and Fieldskit Deinterlacer, Lumetri.  I know that Neat Video slows the job down 4-5x, and for this content, that is acceptable.

However, when I leave the computer unattended for 2-3 hours, the job slows *way* down and "Remaining" climbs past 24 hours.  When I return to the computer and start working on it, speed returns to its normal crawl.

I set the Energy Saver "Turn Display off after" to "Never".  Screensaver was set to go off after 1 hour (now at Never).

GPU usage seems to be pinned around 50%.   Renderer set to MPE-OpenCL.

There's a job just finishing up as I type that has taken over 17 hours to render, when it should've taken around 4 (I know, 61 minutes of 720x486 video should be faster than real-time under normal circumstances).  I have dozens of jobs that I need to process in this way, so the unattended slowdown is untenable.

I recognize this may be an Apple issue, or a Neat Video issue as well.  I also recognize this is a nightmare scenario for SQA.  If it helps, I live about 1.5 miles from Adobe San Jose campus, and I'm willing to bring my system in for testing.