These are the most difficult issues to track down 😞 
Are you using the stable version at nostrudel.ninja or the alpha version at next.nostrudel.ninja?

The stable version works but has some performance issues around caching and the notifications view.
The alpha (next) version has a lot of these issues fixed but also verifies signatures by default, which can cause some other performance issues

If your using the next.nostrudel.ninja version can you try to switch the event verification method from "default" to "Web Assembly" in performance settings? https://i.nostr.build/q6ke8.png