Can't keep up! Is the server overloaded?

Hello good afternoon, I am constantly having this error in my spigot.

How can I solve that?

Warn: https://pastebin.com/xN9wxWnt

regards!

Are players discovering non-generated chunks? It could cause lag if you haven’t pre-generated your world. That way when players travel the server won’t be generating all the new chunks.

Yes, players are discovering the chunks, how can I Pre-Generate them?

Using a Plugin called WorldBorder, you can set a border of your world and then use /wb world fill and then confirm it. It will be slow but once you pre-generated a world there won’t be any lag due discovering new chunks. Also while running /fill it will be barely play-able so set aside some time for it.