Is there a way to add a mesh collider cheaply

Each time that I create a mesh collider to an object it freezer for a few moments, is it possible to create a mesh collider without taken that much time

If it is possible for you to create the collider before you need it then that would be a better way to do it. Mesh colliders are expensive in general, and creating it while playing will take some time depending on the number of verts of your mesh.

If you do not generate the mesh at runtime then you should create the collider before you need it (by assigning a mesh collider in the editor and disabling it) and just turn it on when you do.