Answer: quickest

AnswerCrossword Clue
QUICKESTMost snappy
quickestLasting or taking a short time
quickest(of a person) Prompt to understand, think, or learn; intelligent
quickestMoving fast or doing something in a short time
quickest(of a person's temper) Easily roused
quickestHappening with little or no delay: prompt
quickest(of a person's eye or ear) Keenly perceptive; alert
quickestQUICK, speedy (swift (speedy))