RebuildConveyorList occurs in a thread, happens periodically, and should never add any lag unless you are on a single core processor (which I don't even think exists anymore). That being said, something else might be going on. The best thing to do is to provide a save for me to look at, and I can check it out when I get a chance. It may be a complexity issue that I can solve by looking at how complex your ship is in code.

I had a big solar assembly with many rotors, removing that solved the problem. So every thing is fine. Thanks for the reply!