When you say cold cache, did you clear the os page cache as well as the postgres buffercaches? After setup.sql, the cache will be warmish - I get 4ms on the first run. I'm using postgres 17.5

See https://github.com/ethan-seal/ors_expensive/blob/main/benchm... where I use dd to clear the os page cache.

This article by pganalyze talks about it: https://pganalyze.com/blog/5mins-postgres-17-pg-buffercache-...