In my experience, the best benefits gained from caching are done before the backend and are stored in RAM, so the query never even reaches those services at all. I’ve used varnish for this (which is also what the big CDN providers use). In Lemmy, I imagine that would be the ngnix proxy that sits in-front of the backend.
Yeah, that’s exactly why I’m asking this question. All the effort seems to be going into the DB – but you can have a horribly shitty DB and backend but still have a massively performant webserver by just caching away the reads to RAM.
I didn’t see any tickets about this on the GitHub, which is why I’m asking around to see if there’s actually some very low-hanging-fruit for improving all the instances with a frontend RAM cache.