I’ve made a SpongeForge server for 1.12.1 (I guess I should expect problems since it’s an experimental build) so I can learn how to make plugins and test them, however whenever I join, the server freezes up and times out.
I’m not sure if it’s something I may have done or what’s causing the problem. Anybody have any ideas?
Here’s my logs, if they’re useful:
Minecraft Server; Forge Server
The only error I get is that the server “Can’t keep up”, but after that I get kicked and the console is frozen.
The forge log appears to be chopped off at the bottom (could be due to pastebin’s size limit).
It would be useful if you could run the timings command so we can see if there is anything unusual.
Info on timings here: Commands and Permissions — Sponge 7.2.0 documentation
That’s where all my Forge logs end.
There’s the fml-junk-earlystartup.log that I didn’t include but I think it’s just been overwritten when I just ran the server again to run timings.
(Timings when I joined and there was lag at first.)
(Timings after I restarted and ran it again, this time no lag.)
I joined and there was the same lag as before, but this time it lasted only like 15 seconds so I wasn’t kicked, and I had control of the console again.
Now when I start the server there is no more lag. 
So that’s good I guess, but I’ll try again to see if a new server has the same issue.
EDIT: Ok so I made another server and it had the same lag problem on first join (but no time out so that’s good), here’s a timings for that one as well.
I just ran a spongeforge server of the same version and didn’t notice any unusual amount of lag. Not sure what’s causing it for you. It could be something in the world, maybe load up a flat world and see if it has lots of lag.
And since you’re using the experimental builds, always be sure to update regularly.