Slow as in slow turning over or just takes a longer amount of time to start than usual?

If its turning slow depending how close your starter is to your exhaust that could be the cause.
Im not sure on the mondeo if the starter is at the front or back and where the exhaust manifold is but if they are near to each other and the heatshield is missing this could be whats causing your slow starting.
Had the same issue on a xr3i years ago