I joined my server and i created some portals (mekanism), then it crashed for some reason (2 crash reports, one of them is 1 tick took 100 seconds):
https://paste.dimdev.org/itovagedot.rb (ConcurrentModificationException)
https://paste.dimdev.org/matizuqabe.cs (ServerHangWatchdog)

After rejoining my client throws me theese errors:
https://paste.dimdev.org/kehakupoyu.rb (Null pointer)
https://paste.dimdev.org/aciyuxeken.rb (Null pointer)
https://paste.dimdev.org/idapetidaj.rb (Stack Overflow)
(theese also happened with singleplayer)

Also the overworld is now lagging without portals.
Disabling the mekanism portal fixed it for now

I remove it from the server for now, because it unplayable right now...

You have far too many mods installed for me to be able to even consider reproducing the issue.
Please remove as many irrelevant mods as possible (if it happens with vanilla portals, then get rid of mekanism too). Optimally there should only be BP and maybe one or two other mods left. Once done, re-post the watchdog crash report.
If it happens in SP as well, then get rid of the server.

If all those errors happened one after the other without restarting the game in between, then I don't care about any of them except for the first one (which I guess would be the ServerHangWatchdog).

Disabling the mekanism portal fixed it for now

Disabling as in un-setting the frequency, as in removing the block or as in disabling them in the BP config?

Disabling as in un-setting the frequency, as in removing the block or as in disabling them in the BP config?

Disabling it in the BP config, But the overworld still lags.

You have far too many mods installed for me to be able to even consider reproducing the issue.

I attempted to use it in my modpack

I am currently experimenting by slowly adding more mods from the modpack to a localhost server and a seperate client

Something different happened. The portal cloned me, and I get pushed around

Server log:

[14:22:17] [Server thread/WARN] [minecraft/NetHandlerPlayServer]: ErdbeerbaerLP moved too quickly! 13.47313286255024,9.0,29.72815505770329
[14:22:17] [Server thread/WARN] [betterportals/portal]: Ignoring use portal request from EntityPlayerMP['ErdbeerbaerLP'/0, l='world', x=8,48, y=71,00, z=-3,25] because they have an outstanding teleport.
[14:22:17] [Server thread/WARN] [betterportals/portal]: Ignoring use portal request from EntityPlayerMP['ErdbeerbaerLP'/0, l='world', x=8,48, y=71,00, z=-3,25] because they have an outstanding teleport.

For any separate bugs, please open a separate issue (and include required info for reproduction there), so that they can be tracked independently.

@ErdbeerbaerLP
If you're still busy figuring out which mods are required for this, then I think you can pause that for now. After lots of testing I've been able to reproduce the world lag on my machine and the watchdog crash is probably just the same thing but worse enough to a point where a single tick takes > 60 seconds.

Ah, but i still have some things to report (1 more report incomming)

When you have the time, please give 0.2.5 a try and report back whether it fixes the performance issues.

I tested it and it seems to be working lagfree.
But the screen is flickering when moving. (I gonna record a video and create yet another issue)