Looks interesting, but the main page claims it has support for a lot of languages, but according to this module page it only supports javascript, typescript, and html?
From my experience, most of the packages listed there with TODOs have basic support with some extras, but are lacking documentation and testing. For example rust, supports syntax, formatting, lsp or racer, cargo and other goodies.
I had a fairly large config and kept running into problems with speed. I gave up late last year and tried doom and haven't looked back. Very fast compared to what I had hobbled together.
It might be a bit out of date now but at least 90% still holds.