This is actually bad for the instance. It costs a lot more resources to send and fetch submissions from a bunch more instances.
That juicy /all feed though, worth it.
Eh, even with a LOT of subscriptions lemmy really isn’t that heavy.
It’s the outgoing federation (I hear) that really starts taking more resources
an ELI5:
When you set up a lemmy instance, it has no idea other instances exist. It’s like throwing you into a web browser with no search engine. You don’t immediately see every single website, you have someone tell you about a cool website you found, and then you type it into the address bar, and save it.
It’s kind of the same thing with Lemmy instances and communities. Once a user types this syntax into the search prompt:
!community@instance.com
It will try and contact instance.com for that community. If it exists, the user can subscribe and the instances will now receive and send new posts to each other.