In the MSTS AE the "Default performance" parameter can be set from 0 to 100 for AI trains. In MSTS low values correspond to low accelerations and low maxspeeds. In OR this does not happen.
Two demo activities for route USA1 are provided here, that differ only in the value of such parameter for the AI train. In the activities an AI train starts in parallel to the player train.
In activity Testpeformance_new.apk Default performance is set to 6; running such activity with MSTS the AI train accelerates very slowly and reaches a maxspeed between 6 an 7 mph.
In activity Testperformance_new_100.apk Default performance is set to 100; running such activity with MSTS the AI train accelerates much faster and reaches much higher maxspeeds.
When run under OR the AI accelerates fast and reaches high maxspeed in both activities, with no visibile difference between the two activities.
The parameter is very useful to modulate speed of an AI train in an activity, and is also prototypical, because in general real trains do not run always at full power, even when this is compatible with speedlimits. It is also useful to get AI shunting at reasonably low speeds.
Fix committed (as an experimental option) in release x.2341.