Just updated my Minecraft 1.18.2 server to use FishOfThieves 1.0.8-rc1-fabric, and I'm noticing a significant amount of new lag and latency on the server now. I ran a Spark profiler on the server, and noticed this in my results:

Basically, consecutively expanding the most expensive thread boils down to these two methods, with specialThunderTick taking up nearly 13.5% of the server thread.