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!
My local instance hasn’t upgraded to 1.18, and it’s 404-ing me when I tried to load this community in that instance. Another friction surface absent with this lemmy.world account of mine.
You could reach out to your instance’s admin, asking them where they are at with the update?