please help making a loop faster

[ThomasL]

Why would you use this function under these circumstances?
That makes by no means any sense.
Do you understand the docstring?

"""
Inputs:
- x: A numpy array of images of shape (N, H, W)
- w: A numpy array of weights of shape (M, H, W)
- b: A numpy vector of biases of size M

Outputs:
- cout: a numpy array of shape (N, M)
"""