screenshot

I'm using Spark mod to check this. It lags the server even when small dungeons are being generated, like towers.

use the issue template.

The mod is pretty performance heavy, especially older versions.

If you really mean this serious use a proper java profiler.

Also install phosphor if you haven't already.

Btw, the newest version runs just fine for us. Older releases do have a problem when generating the stronghold types, that fix won't apply however if you didn't reset your configs.