[zrail]

PostgreSQL defaults (last I looked, it's been a few years) are/were set up for spinning storage and very little memory. They absolutely work for tiny things like what self-hosting usually implies, but for production workloads tuning the db parameters to match your hardware is essential.

[nijave]

Correct, they're designed for maximum compatibility. Postgres doesn't even do basic adjustments out of the box and defaults are designed to work on tiny machines.

Iirc default shared_mem is 128MB and it's usually recommended to set to 50-75% system RAM.