Server.jar from official minecraft web site and launcher can be use a lot of RAM and Processor on FTP Server (in 1.13.2 it use 4-20% in late game but in all snapshots (18w47a-19w09a) it use without players 100% processor and with 1-4players it use 200-500% processor, RAM is on 2-4GB in use). World can be dosen't loaded more than 10 minutes. When I run server he work after 3-5min. after start and in next time(20min-2h) he have an issue with load chunks and we doesn't see in game reloading client work 2-3times and next we have to turn off and turn on server but that is a Loop and we can't repair this we try play in oldest versions (we start in 19w09a and we change to 18w47a( it's lastes version were compile work)) but on all of this versions that work the same way. Server some times crash mut it was beacause we use a max RAM of available. Sorry for but english but it is(was) my first time when i write more than few words in text. I create more than 10 minecraft servers but it was first time when i create on snapshot maybe it is my fault.