I downloaded this mesh on this site and imported it into ue4, already removed duplicate vertices and duplicated faces and remapped the uvs. But it doesn’t work, when I look at the mesh or its parts separately it starts to lose performance.
If you import the object with the “combine meshes” option unchecked and place a single piece in the world, it will also give the same lag if everyone were together. Weird…
There is no reason it should be impacting your performance based on vert count so it must be a geometry problem. I can’t download the model and check for myself right now, but I would advise you to carefully examine the connection points and move some surfaces to check that the model is in fact connected together. It’s a common problem, two verts on top of each other have not been merged.
I already made the necessary adjustments in 3ds Max but I was not successful.