This site is currently struggling to handle the amount of new users. I have already upgraded the server, but it will go down regardless if half of Reddit tries to join.
However Lemmy is federated software, meaning you can interact seamlessly with communities on other instances like beehaw.org or lemmy.one. The documentation explains in more detail how this works. Use the instance list to find one where you can register. Then use the Community Browser to find interesting communities. Paste the community url into the search field to follow it.
You can help other Reddit refugees by inviting them to the same Lemmy instance where you joined. This way we can spread the load across many different servers. And users with similar interests will end up together on the same instances. Others on the same instance can also automatically see posts from all the communities that you follow.
Edit: If you moderate a large subreddit, do not link your users directly to lemmy.ml in your announcements. That way the server will only go down sooner.
How is that ultimately any different from how usernames work in a centralized system? If you have a username on reddit, that's your username no matter what the subreddit/community. I understand how lemmy is analogous to email, but I'm not sure it's the right model for a link aggregator and discussion system.
I guess what I'm saying is that decentralization may be better served if instances operated as an internal load balancing system rather than strictly separate servers. This would also help with an influx of new users, so you can just spin up a new instance and lemmy just flexes up without having to manually direct users to sign up on a specific server/instance.