The site currently runs on the biggest VPS which is available on OVH. Upgrading further would probably require migrating to a dedicated server, which would mean some downtime. Im not sure if its worth the trouble, anyway the site will go down sooner or later if millions of Reddit users try to join.
Its moved to https://join-lemmy.org/docs/en/contributors/01-overview.html. Not sure where you found the old link, would be good if you can update it.
Its nice that Reddit is promoting Lemmy like this. I just wish they would give us more time to optimize the code so that it can handle all the new users. For now it looks like many Lemmy instances will be completely overloaded from Monday, but lets see.
For now admins can already add custom themes to their Lemmy instances. Its described in the docs.
You can setup a new instance (or join an existing one), then follow remote communities you are interested in. All the content will get mirrored over time, and you can interact with it seamlessly.
We are currently removing websocket and switching to http, so that should be much better soon. Load from the frontend and Rust backend are both pretty low for now.
No the problem is really with SELECT queries, because they do a lot of processing for the hot rank.
This site is hosted on a VPS from ovh.com. I upgraded it from 4 vCPU to 8.
FYI we planning to rewrite some parts of the api soon. You can check the api issues to get an idea. So this is a good time for suggestions.
I see, fixed the link in that post.