I know that some unions increase lag while some unions reduce lag. From my personal experience, all unions have done is increase lag. I have a question about this union I made.
For my computer (a GTX 1660 Super with a Ryzen 3700X and 16 GB ram) it gave me a solid 60 FPS on an almost flat baseplate while using that amount had almost no lag and my GPU/RAM usage was fine. But I would recommend NOT using 3,200 of that union. It’s better to use meshes then. If you don’t know how to model then I can help you on that.
like @Crazedbrick1 and @Temateite said, just use blender or something
but if you are going to use unions make sure to set their collision fidelity to Box unless it NEEDS to be preciseconvex
also im pretty sure unions will only cause lag if they’re made up of like 20+ parts, but at that point just use blender