1) I'm sorry if it seemed like I was trying to imply that there was a fix for your situation, Art. I was simply saying that Chris (from Rational I believe) might be able to test version 6 for this HF roll off issue, see if it matches what you've observed and document it.
2)When you upgraded (I assume you upgraded a 2011 to end up on High Sierra) did you convert to APFS or stick with the tried and true?
1) Chris' response can be seen in #9.
2) I did not convert to any of these versions of "APFS":
APFS Airport Police Fire Service
APFS Accredited Personal Financial Specialist
APFS American Portfolios Financial Services
APFS Agua Prieta Family Shelters
APFS American Pioneer Financial Services
APFS Army Physical Fitness School
APFS Associate of the Personal Finance Society
APFS Adequate Prime Farmland Soil
APFS Afloat Prepositioning Forces Ships
So far it appears the "upgrade" was to APFS "Apple Piece (of) Fucking Shit", but all tried has not been true ;^).