https://xenforo.com/community/threads/out-of-memory-if-user-is-following-too-many.58734/Remove the 1k limit regarding the amount of users you can follow.
https://xenforo.com/community/threads/up-the-users-you-can-follow-limit.109011/
tl;dr Xenforo limits exist because the forums get laggy and unusable otherwise.