pg_stat_statements is useful, but it isn't completely free, e.g. [1] (admittedly from pg12, which is three major versions ago).

Most people should probably leave it enabled, but if you have a database with a very defined and understood query pattern, then it might be worth running perf and checking if it is costing you.

[1] https://www.alibabacloud.com/blog/postgresql-v12-how-pg-stat...