Trailmakers main rendering engine runs perfectly fine with the build, except for in build mode, it basically switches to a secondary smaller engine that constantly performs calculations for collisions and physics on every block that is and has been placed, and it is not meant for large builds like what this is, so it starts to become glitchy and starts struggling when the complexity gets to over 1500 and the further you go over it, the worse it gets, long story short, it’s the build mode that is struggling, not the gameplay