I've found that with a traditional RDBMS that schema and query structure often count for as much or more over specific tweaks. I have pushed for using a single-node CockroachDB configuration for local/development instances and then using hosted (cloud provided) PostgreSQL for production. The use of CDB is to allow for the potential of future scaling as needed, where PG is more widely available in an externally supported means from the start with CockroackLabs (cloud) as an optional step as well as self-managed.

Just my own $.02, you can definitely tweak an RDBMS, but it's definitely going to vary by use case and more work can definitely be needed (indexing in particular is a bit of a dark art).