I believe it would theoretically perform better, but it’s often unnececary and forces you to make sacrifices such as collisions, quality, and ease of editing.
I’ve wanted to explore this for a while because I’m more comfortable in blender than I am in studio. I think it is possible, and in lots of game engines this is the standard process for making a map. This would allow you to use PBR textures and all of the other advantages of modelling in a dedicated mesh editing software that come with higher quality maps. One caveat for this is that by default, collisions on meshes aren’t great. You could get around this by disabling collisions on the mesh, and blocking out the walls/floor/anything else in studio to have a high-performance collision solution.
Experiencing Blender for a long time now, I highly suggest you make your map in studio then import it into blender to decimate everything. Lag is sometimes dependent on the amount of tris (triangles) in a object. Hopefully this helps, any questions please ask.
This idea would be doing more harm than good. Besides the horrible collisions, you’d also run into problems such as it being a huge time waster from switching from Blender to Roblox Studio to continously fix/update the map.
For optimizations, I suggest using Performant Builder and then just using MeshParts responsibly, I created a topic on how to do so here.
I believe this would only work with low poly maps, due to their already low and simple triangle level and style, however with high poly maps, decimating it just so it hits under the 10k tris mark sounds very hard until it glitches out. This is also a problem with open world maps, where reducing lag is the biggest challenge to overcome.