Any chance this can be improved?

How many grids do you have on the multiblock?

No idea, hard to tell with 30 players.

Just noticed that I posted this in the wrong repo, sorry about that.
Want me to move it to EFab?

It's ok. Most likely the issue is multiple grids on the same efab multiblock and that issue is already fixed and ready for next release

Is that commit already on github? I would like to put the fix already on the server side.

That's too complicated. EFab depends on a heavily modified McjtyLib so you would have to compile all my mods from github. Also all the clients would have to be updated as well

The clients don't need to be updated as the grid calculation is only done by the server, except you do something out of the ordinary.
This also shouldn't be complicated if the fix is not a complete rewrite of multiple classes.

No but a lot of other things have changed in the mod too. You could try to get an older version and try to do the same fix on that. It is not a complicated fix

That's why I'm was asking about the commit to see what was changed to fix this issue.
It's at 9% now so I really would like to get this issue fixed asap and also test if it actually fixes this issue.

Is it this fix you were talking about? McJtyMods/EFab@e32edde

yes indeed. Note that yesterday I released alpha versions of all my mods. But maybe that's too risky and complicated to distribute to all your uses. In any case, the commit above is the fix you want

Hm, that removed code doesn't use func_180495_p (getBlockState) which is the main issue.

It does. Indirectly. I'm pretty sure that will be the reason. The removed code makes sure that there is no cascade of updates which all use getBlockState