I'm running it on my own server and performance is quite acceptable. Picking the right client is very important, though; Element isn't always the fastest, and I find Cinny's UX to be much better for general chat, which is clearly very much… inspired by Discord. On the other hand, Element is ahead in terms of features and protocol support (like the (live) location sharing feature), but Fluffychat has the superior mobile app in terms of general look and feel IMO. On the desktop, Nheko is incredibly fast, being written in a native language and being optimized for performance and all, but I don't use it because I just can't get used to the design.
When joining huge chat rooms like some of those on the matrix.org homeserver, it can take a bit for the clients to sync up and get going. Performance is getting improved all the time, especially in terms of quickly joining a room. Latency also doesn't help, the protocol requires loads of round trips for the JSON payloads to go back and forth, so if you're not near your homeserver you're going to see some annoying problems.
I recommend giving the platform another quick try using https://app.cinny.in/ which to me feels very Discord-like in terms of snappiness.