@KEV6172 Found your issue. Coming back to a high poly count.
Your 10 LOD sections all have per-poly collision enabled, aka complex collision. It isn’t an issue in the level because by default, the Unreal project uses simple collision. I’m guessing it’s an issue in the mesh editor because the complex collision is recalculated too when you move the simple collision.
Turn off collision on all your LODs and use a multiconvex hull simple collision or add multiple box collisions. You can also create custom collision in Blender. The mesh I uploaded above has custom collision made like that. Let me know if you need a tutorial on that, I think I had an instruction file somewhere.
PS: I THINK this might also be solved by reducing the number of materials, but then you’ll have to re-texture the mesh.
PPS: You can check the stutter in action by opening Task Manager and noticing the memory usage (RAM) of your Unreal project. As long as you keep moving the collision, the memory usage will begin to increase dramatically.