I was playing around with the speed/ke calculating spreadsheet that I made a while back plugging in different arrow weights and such and as far as ke is concerned, at my draw weight/accessories/etc... 440 grains seems to be the optimal arrow weight for my setup. By that I mean when I go over 445 grains, my ke starts to drop. Does this mean my bow is most effecient with a 440 grain arrow and it is actually hurting me to go to a heavier arrow? At what point does it become fruitless to shoot a heavier arrow at the expense of ke & trajectory?

Coincedentially, my ACC 3-60s with feathers and a lighted nock with 100 grain broadheads weigh in at 442 grains and shoot 287 fps with almost 81# of KE.