Now, completely without benchmarks, I can tell you that my workplace has migrated from Oracle to Postgresql and performance is essentially the same: a few things were a little faster on Oracle, a few a little faster on PG. All revenue is directly or indirectly dependent on the database systems, which have been continuous for 20+ years: this is not a side-project.
PG administration is much, much faster. Starting an Oracle database always involves a wait similar to booting an elderly operating system. Starting a PG database is fast. Things that Oracle will want to up-charge you to an Enterprise Edition license for, PG has for free. Want to spin up a new machine? No need to negotiate a new license with PG. The cost of the Oracle license would routinely be so large that you need to buy awesome hardware to justify it. You can install PG on anything, and justify it.