server booting, then terrain not generating

Hey! I have been experiencing a problem with my server where the server boots fine, then when a player joins, no terrain loads, then they time out.

If I download the world on singleplayer (like I did here) then it takes about 2 mins till terrain gens.

I think its to do with the world file size but can't be sure.

its not that

the server boots then crashes, the files are fine, also i dont think its lag, I can play other servers just fine?