Dynamic meshes causing hitches

Is there any way to speed up recalculation of dynamic meshes? On the Vita, I'm getting slight but noticeable hitching when I do this:

Code (csharp):

1.  
2. Vector3[] vertices = mesh.vertices;
3. for ( int i = 0; i < vertices.Length; i++ )
4. {
5. // do something to the vertices
6. }
7. mesh.vertices = vertices;
8.  

And yes, I've tried removing the code that actually does something to the vertices and confirmed it's not that

This isn't an issue on other platforms.