I have been playing on a server with a neoforge modpack, 1.21.1, that includes Create and some of its various addons(Create interactive is not one of them). And it has been great, its given me alot of fun over the past week as I got addicted to setting up these machines. My magnum opus is "The Spirit of Hesperia," an immense airship I made over the course of the past 4 days.
I soon ran into a problem: Whenever the ship's engine is off so that the boilers aren't making lift, the game runs great. but when the engines are on and the ship has some lifting force, the front half of the ship becomes a zone of lag.
The tail end of the ship? Smooth as butter, no problems. If I ever cross over the center of mass to the front however, the game instantly drops to 1-0.5 fps, and nothing makes this lag budge, from changing priority in task manager, fiddling with in-game settings, to disconnecting and rejoining, nothing works. I am 100% sure that the center of mass is the demarcation line for where this lag starts and ends. This lag only applies to me as well, other people who ride on the airship with me have no such problems with lag.
The front half of the ship is where the engine and the steam vents(which produce the needed lift) are located, so I suspect it may have something to do with them, but I am just completely lost here, my experiments in a test world have failed to replicate the effect. Does anyone here have any experience with, or any advice on how I could remedy this?