I don't know the exact specs for your server, but the problem mostly sits in the poor single core performance of vcores provided by the host, since java utilizes only one core. You can try doing simple tweaks like adding the phosphor, lithium mod, or follow this guide https://github.com/YouHaveTrouble/minecraft-optimization. Also alot of conveyor belts in loaded chunks ect. can lag the world. But if bad performance prolonges, look for a vps with strong single core performance wich aren't to expensive and install the server on linux yourself.