Unity5 Procedural meshing slower than in Unity4?

Hello Unity Answers. I recently got back to developing games in Unity and I downloaded Unity5. My previous project involved making meshes from code, and I wanted to continue with that project so I ported the code to Unity5. Now here’s the problem: With unity5 a **single untextured face ** takes up to 20 seconds to render. I switched to Unity4 with the same code and it renders instantly. This seems very odd since one would assume greater performance with a newer version, right? Is there some new option I should disable to make it load faster?

Note: When I say ‘render’ I mean run the scene in the editor

Edit: The code I’m testing with is just the example on Unitys docs: mesh

I found the error. It has nothing to do with Unity5, I just accidently extended a class with MonoBehaviour when not needed. This caused several warnings and slowed down the build process.