Synonyms for Quickness (same or very similar meaning)
WordNet sense 1 (skillful performance or ability without difficulty):
adeptness, adroitness, deftness, facilityWordNet sense 2 (intelligence as revealed by an ability to give correct responses without delay):
quick-wittedness, mental quicknessWordNet sense 3 (a rate that is rapid):
celerity, rapidity, rapidness, speedinessFrom the ODE community, based on WordNetadd/edit