Going pixelated and/or slowing badly

PC editor, Windows 10 x64 professional.  RTX 3090 Ti, 32GB (very) fast RAM, SSD, plenty of free space, all software/firmware/hardware up to date (LR v8.4).  130 Mbps internet @PC89_2.  Other apps running or not has no effect.  Anywhere from 500-2000 photos loaded (All Photos), makes no difference.

For the first couple of months since starting to use Lightroom, it was very fast and practically never glitched or crashed.  For the past few months now, it VERY often slows absurdly and/or suddenly the image turns extremely pixelated (like 400x267 on an image that is and was just showing at 7826x5217) when performing various functions.  Sometimes while using AI remove, or while zoomed in doing healing brush, or just color correcting.  Sometimes waiting it out 30 seconds to a few minutes sees it return to normal, sometimes not.  And even when it does revert, it just happens again a few moments later.

This makes editing nearly impossible, and absolutely impossible to do efficiently.  Please advise, I do not appreciate recurring payments for something that cannot perform.  Professional photographer, time is money- this has caused massive delays to client albums and I am losing rapport/potential clients now.  This is my second time requesting help on this issue.