In response to the question, the reference to harder work relates to Lomcevaks suggestion that everything was normal, but that the premature arrival of the end of the runway precipitated the lower than usual rotation speed.
I do not wish to flog a seemingly dead horse, and so am happy to move on from the takeoff, simply noting that nothing that has been said would contradict the possibility of the engine developing less thrust than the pilot was expecting for the given throttle setting. A question which is central to the accident sequence of events