That is only when the schedule exactly matches the locomotive's capabilities. Schedules in IR are not decided by loco's performance, they are decided by track occupancy and platform availability etc and are usually far below the locomotive's capabilities. I.e., An ALCO is capable of hitting 120kmph, so a train running with a schedule of 50-60kmph average speed may not be affected much. But a train with a scheduled average speed of 70-80 kmph will definitely struggle. In this case, it is a passenger train and that's why the schedule is slow, it's not because of any limitation of the diesel locomotive.