So, this may be a slightly unpopular decision, but we're banning elytra launchers. Now, this isn't because we hate fun (honest!), it's entirely to do with performance. I've been testing things for a little while, though I haven't had a chance to do it properly until today due to lack of time. I have now, however, confirmed that it is elytra launchers causing the excessive amounts of lag we've been having on the server in the last month or two. This is for the benefit of all players so we can all have a (hopefully) lag free experience.
Why are we doing this?
Minecraft works by calculating everything to show you 20 times a second. Each of these calculation runs is a "tick". When we get server lag, it's because the rate at which the server can run these ticks is dropping significantly below the 20 mark (it can't move on to another tick until the previous one is complete, which is why you get blocks popping back. It hasn't had time to process your action yet). One thing the server has to do, is calculate entity collision. Entities are things that aren't blocks, like mobs, boats and dropped items.
When you have lots of entities, obviously the game has to work out things for all of them. Just having lots loaded gives the server more to do, but when you start making them all bump into each other, that's when it gets bad. The server is then having to calculate the collision data for each and every one of them against every single other entity it is touching. So when you put 200 boats (which is what I found just now) together in a pile, it's calculating collision data 40000 times, just for that stack of boats.
That's a lot of calculating. And that is why it needs to stop. I removed this stack, and the server went from fluctuating between 10 and 13 ticks per second, to a full and steady 20 within 10 seconds.
What does this mean for me?
Well, you can't make launchers any more. You're just going to have to jump. Sorry. I will be putting in place measures to try and curb this for those who won't know, but staff will be receiving the ability to sniff them out too. Those who have made them in the past will not be punished, and those who make them in the future will just have it explained to them, and the launchers removed (unless it becomes clear they are doing it on purpose, in which case staff will have discretion to deal with them).
You can either remove them yourself, or we will try and find them and remove them for you, but either way, no hard feelings. I'm just glad we've got this figured out!
If you have any questions, please ask below.