We've had the server for up around a year. I've been banging my head against the server for a week trying to figure out why we have dropped to terrible tps in spikes. I eventually removed F&A as part of the testing in a separate testing environment and the Forge log then told me it was skipping tarslime entities... around 25-THOUSAND of them. I think some may have been in spawnchunks so they kept on spawning, definitely plenty spawned near our main build area over the months as well.

It's not the only thing going on but it has been significantly contributing to our woes,

We need to either have the tarslimes despawn when not near a player (like vanilla slimes), or else introduce some kind of cap on them. I've nowbrought the InControl mod in to limit them at 10 per chunk average, and 500 in total in the whole game for now.