If during flying training a loading calculation and performance calculation was made for every single sortie would this go a long way to eliminate performance related accidents?
Possibly, but it might actually be counter-productive, in the sense that during training the load is rarely going to be more than 2 up (P u/t + inst), no baggage and almost always from the same strip, so the results will almost always be virtually identically satisfactory, potentially leading to a blase attitude and a false sense of security.
It would definitely be of considerable benefit to always do such calcs with an instructor if landing and taking off from a different airfield - particularly grass / short / sloping strips.
And that leads into another discussion of the PPL syllabus, regarding the variety and types of airfields that students could / should be introduced to during training rather than after.
SD