There are many lemmy instances in the world, but currently most people are using lemmy.world. This is why everything has gotten so slow.
You don’t have to delete your lemmy.world account, but check out https://lemmy.fediverse.observer/map it’s a geo-based map of lemmy instances – explore stuff nearest you, pick one, sign up, search , subscribe and begin interacting with your favorite communities. It’s easy, free and it will be faster. Try it!
I just put the url in the search box on the Lemmy webui sand search. I find a lot of the time it says nothing found but if I click search a second tinder it finds it so it must be a bug. Then click the community and subscribe.