Just to rule things out, I upgraded the server to 8 vCores and 32GB RAM. I set db buffers to 16GB and Unicorns to 16. Other tweaks back to defaults.
Unfortunately the upgrade did not do much. Rapid discussions are constantly freezing, even with mediocre activity.
The performance is miserable nowadays. I guess I need to start looking at Prometheus etc. I am 95% certain that the performance of the software has seriously regressed since v2.3.
Brother @Iceman’s comment was mostly neglected in September. He reports that the chokes happen no matter what hardware he is throwing at it?