What finally made War Thunder click for you?

Finally worked this out, so here is the write-up I wish I had found. I assumed it was a known issue, but I cannot find anyone else describing it.

Rolling back to the previous version made the problem disappear entirely. Thanks in advance to anyone who chips in.

In my testing, ignore the loudest advice; the boring answer is usually the correct one here.

Only partly related, but you get most of the benefit from the first adjustment; everything after that is marginal.

Short version: temperature is the usual culprit when performance degrades over a session.

Worth a shot before anything drastic.