I am playing GWE again for the first time since the last updates. It seems the acceleration of the class 166 is made a bit slower than it used to be. This impacts the timetable. You simply cannot complete a full length run and arrive on time, you will be 3-4 minutes late. I believe the issue is caused by the slow acceleration of the class 166. Starting from Reading it works nice, but once the distance between stations is less than 2 miles, you start loosing from the timetable. Even strong braking will not help you here. This simply is not good. Because the modelled train behaviour may deviate from the real thing, this may have impact on the timetable. Is this bad? For me it is not, but they should match anyway.
The physics is realistic. The timetable would have to be remade to match the physics but that would have taken a lot of time.