TLDR: Unfortunately, no. Currently Flarum is not very cache friendly.
We can't simply take responses from the API and cache them, because for logged in users, API responses also contain read status or private discussions. At the same time, it is not easy (or even possible) for the cache server to determine just from HTTP response headers if the data are for a logged user or a guest. In addition, Cache-Control headers are not used by Flarum. Forcing the cache server to ask for session state, or even maintain state, is anti-pattern. Yet the API is the slowest part of Flarum. The furthest along cache implementation so far is @rafaucau with Litespeed Cache implementation https://discuss.flarum.org/d/29475-litespeed-cache-for-flarum
