RA2/YR IL timing problem

I have two 'best' times for Yuri's Revenge Allied Campaign Mission 2:

Real time   Game time
06:27.128   06:46
06:25.965   06:47

For real time I started timing on the first frame the sidebar and bottom bar appear on screen after loading and ended timing on the frame Mission Accomplished appeared. Despite being over one whole second faster, game time said I was slower. What causes this problem? Because both games use the same engine I'm sure it applies to every other mission too.