As an instance owner I can say lemmy.world is a bit of a troublemaker as it will constantly halt and resume federation activities in a very bursty way and cause momentary spikes in resource usage. I have now upgraded the instance enough that it’s not really a problem, just an annoying observation.

Having said that - feel free to test run my instance! The only problem I am currently aware of - gmail outright refuses to accept email from it, so verification is impossible. Thanks, Google! Have not had any reports about other providers, though!