Quick Union/performance question

I have a lot of Union in my game would it be better if I just turn them into mesh? For performance?

Onions in your game is like a block but 3x it’s value so you’re game be laggyyy. Also yes meshes help

“Turning” them into meshes by directly exporting and re-importing them doesn’t improve performance. The polygons are still gonna be the same

Best way to optimize your assets is just to make them in blender or some 3D modeling software.

Roblox is atrocious at creating meshes by directly exporting studio made items.

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It really depends on your use case, CSG parts support instancing as well as LoD so depending on how you take advantage of these features it shouldn’t be that big of a deal.

Roblox still solves really complex UnionOperations rather inefficiently so creating these in a third party software like Blender could greatly benefit you if you can fix said inefficienties, i.e. your Tris or Triangle count.

Both MeshParts and CSG parts benefit from LoD and instancing as long as you meet the right criteria, and both of which have one special feature over the other so it really comes down to, like i mentioned before, use case. Below you’ll find a comparison on the pros and cons for each individual object.


Pros for MeshParts:

  • Making complex objects is easier, with greater control over the overall efficiency.

  • LoD enabled (if RenderFidelity is set to Automatic).

  • Instancing enabled (For objects with the same MeshId within proximity of eachother. Not tied to Color, Reflectance, CFrame & Size).

  • TextureID property which allows for custom textures.

Cons for MeshParts:

  • Unable to edit geometry after importing to Roblox (besides Size).

NOTE: There are a few objects under the MeshPart category, read this for more info:


Pros for CSG parts:

  • Real time CSG manipulation.

  • LoD enabled (if RenderFidelity is set to Automatic).

  • Instancing enabled for identical operations (Not sure about the criteria here, i assume Color, Reflectance & CFrame are not affected by this. Transparency is to be avoided if possible).

  • Geometry can be edited at all times (and through the UnionAsync() & SubtractAsync() API at run-time).

Cons for CSG parts:

  • Overall inefficient for complex operations.

NOTE: The CSG APIs are server-side only. Refrain from using them excessively as they will significantly drain performance.

For more information on in-game CSG and how to apply it, read this:


Some stuff like real-time CSG may not be applicable here but it’s a good thing to know regardless, who knows when you might need this functionality. But overall, MeshParts > CSG parts. It’s just more convenient and you won’t be needing the extra bells and whistles that CSG offer you all that much anyway. By applying the above you should be able to decide what suits your situation best.

Good luck.