I don’t know if I’m doing something wrong or if the servers are currently under heavy load, but they feel very slow.
Uploading my profile picture took 30-40 seconds, and joining any rooms takes more or less the same amount of time 
It seems this was mostly caused by the client itself. Switching to FluffyChat seems to have solved the slowness. Or at least, it was a transient problem.
Hi there, Welcome!
Depending on the client that you were using before, It could be that you tried to join a big matrix room and that causes some slowness overall. What happens if you try to use a client like ElementX (the new version of Element?)