In a normal world, there's a little lag right as I start, but in a Lost Cities world, the lag is extreme.

It almost makes the game unplayable, which is unfortunate because I really wanted to play with this mod.

I do have Terralith, Tectonic, and TerraBlender enabled as world generation mods, and a couple others that add and enhance biomes.

What is happening is double doors from the Serilum mod will open and close at the same time when clicked, this only happens in worlds with Lost Cities enabled..

This lag also causes blocks such as chests, furnaces, and other functional blocks to be uninterruptible unless your hand is empty.

This lag is only severe on any world with Lost Cities enabled

Not sure if related, but here's a spark report when a server was running into crippling TPS issues while a few players were in the lost cities.
https://spark.lucko.me/khQ9Epvk0D

I scaled back to the older version, version 7.0.4 for Forge 1.20.1, the problem seems to be in 7.1.0

Same here. Perhaps it's the number of mobs spawning in the cities at night or something; I'm unsure.

Same here. Perhaps it's the number of mobs spawning in the cities at night or something; I'm unsure.

If possible, more context please, like what mod is being used and tested with sorely only LostCities or not. And what version.

We haven't found anything that would cause Lost Cities 7.1.0 to be slower then 7.0.4. The opposite actually. In all tests that we did it was faster. However, I'm working on more optimizations that should improve performance even more

I'm getting generation issues that eventually make it so I have to force shutdown. Also a lot of loot generation problems. Trying to see if downgrading helps.

Interestingly enough it did help, not sure why. However, it's still lagging so bad that I can't play with this mod. Log gets filled up with "POI data mismatch: never registered at BlockPos"