"Michael J. Baars" <mjbaars1977.pgsql@gmail.com> writes:
> Somewhere in between release 16.3 and
> release 16.9, changes must have been implemented that make the execution
> engine about two times slower than it was.
That seems quite unlikely, and you've surely provided no details that
would help identify any such problem. My own first guess is that the
newer install was somehow built with debugging assertions enabled
(configure's --enable-cassert option). Those are pretty heavyweight
and could possibly account for this. A second guess is that you were
relying on JIT compilation and the newer install somehow omitted that
(failed to use --with-llvm). Anyway, I'd start by comparing the
output of pg_config from both installs.
regards, tom lane
