Mesh Collider didn't work unless i walk slowly towards it

Its weird. I created a wall example, and i have a collider mesh created (note that collider mesh is way off away from the original mesh therefore it should work fine) and, when i run the game, walking slowly towards the wall, it seems to work. But when my character run faster towards it, boomz, i fly through it.

Hmm. Mesh collider reaction slow? I wonder. Anybody have this issue before? Or is it me and my setting somewhere. Because it suppose to be straight forward. hmm.