Make backend requests lighter and faster

[olabrahmi]

Right now requests take from 1300ms to 2500ms to satisfy, and that's HUGE....! We need a way to make it lighter without caching.

We try to avoid caching as much as possible, since the more real-time the app is, the better. Students use it to find available posts. It wouldn't really be helpful to give them a post that was available 2 minutes ago...