With this issue having migrated, just wanted to comment that it’s still an issue over a year later. The Nether remains completely unplayable on my dedicated server unless you turn render distance to minimum, lower all graphics settings, and turn off RTX.
Happening in my BDS world as well. Also occurs when pistons move blocks.
Actually it appears to be fixed! I hadn’t checked in some time, got into the habit of just avoiding the nether entirely. I’m in version 1.21.101 and was able to load the nether and take a long (multi-thousand-blocks) minecart trip with no delays, hitching, or freezing. Loading time is back to normal as well. Not sure when they fixed it but it appears to be resolved.