Here are a few tips I have for you:
- If you have any skripts, make sure that you minimise the amount of loops that your skripts contain.
- Try not to use a lot of command blocks on your server unless they are all important for the functionality of your server.
- Make sure that the plugins you have on your server are all useful to the server. Don't download plugins which you will never use.
- Try to minimise the amount of worlds that your server has. By using Multiverse, you can unload worlds with /mv unload to stop this from happening or simply just delete worlds which you wont need.
- Make sure that no one is loading chunks far away on your server (around 5k blocks or so)
If you have any other questions or want more tips, feel free to ask on the Minehut discord by using the command /discord in the lobby or simply DM me (Criticyl#0869)
I hope these tips could help you fix your issue