If you're comparing in-process SQLite to talking to SQLite over HTTP you'll probably get a small penalty for any language. When co-located on the same machine, you can probably expect something like ~5ms for JS (just for the event-loop to do the IO and getting back to you).

However, if you have multiple processes reading and writing from the same DB it may actually aid latency due to congestion.

I ran some benchmarks (TrailBase author here and big fan of PocketBase): https://trailbase.io/reference/benchmarks#insertion-benchmar..., where you can see, e.g. the single-process drizzle (i.e. JS with in-process SQLite) performance vs over-HTTP for TrailBase. PocketBase should be similar when not fully loaded. There's also some concrete latency percentile numbers when at full-tilt: https://trailbase.io/reference/benchmarks#read-and-write-lat.... On my machine you can expect p50 to be around 15-20ms.