The best solution would be to NOT use any MeshCollider. The computation of the convex collider (convex hull closure) can be very expensive. And the resulting collider will also be very expensive.

My advice: create a compound collider with the primitive colliders (Box, Sphere, Capsule) and make a prefab with it. This will take a little more time during editiong, but will have much greater performance at runtime.

A quick (and also not 100% perfect) explanation to why MeshCollider are so expensive.

First, let's explain why the primitive collider are so cheap.

• a BoxCollider just checks for bounds, so it is like using the < and > operators a limited number of times.
• a SphereCollider is just a check for a distance from a point, which is not very expensive. It can be further optimized by using the squared distance (which is the case in most implementation).
• a CapsuleCollider is also a distance check but along a line. So it requires first to project onto this line.

Therefore, the order of collider is (cheapest first): Box < Sphere < Capsule.

Now a MeshCollider is just a bunch of triangles. The engine has to check each triangles against collision. Thus: MeshCollider >> Capsule.

With a convex collider, there are some optimizations (not presented here). But basically in the worst case, the physics engine still has to check each triangle.