Forge version: spongeforge-1.12.2-2768-7.1.6-RC3627
Twilight Forest version: twilightforest-1.12.2-3.8.689-universal
Link to crash log: (please use a paste site such as gist, do not attach the .txt or paste the log inline)

Steps to reproduce:

1. Switch to the specified sponge version
2. delete world dir and set seed to 7133479666482362947 at server.properties
3. start server and tp player to 20, 64, 124 (It seems that surrounding this location will cause timeout problems)
4. make a TF portal
5. Enter and return back to over world, Once again enter the TF portal

What I expected to happen:
rapidly enter TF

What happened instead:
Lagging or all players disconnected due to timeout.

edit:
This problem does not occur beyond 400 coordinates.

aikar timing report:
https://timings.aikar.co/?id=fe01ac7e538b412ab94e0c77dbef3438

server log with spark tick analyze:(line 362 start to enter TF)
https://gist.github.com/zhourui123/985d5c39e8ec01c78a4c052c913b16ff

server log with spark tick analyze and Phosphor mod:(line 276 start to enter TF)
https://gist.github.com/zhourui123/603b696b6b5835ee81b9bfc8a0216571

Will assume this is SpongePowered/SpongeForge#2862, is that correct?

Yes, also #769