Sentence:  I would have stood there and died there if left to myself , but Cousin Simmons grabbed my arm in his viselike grip and fairly plucked me out of there ; and then I came to some sanity and plunged away with such extraordinary <WSD>speed</WSD> that I outdistanced Cousin Simmons by far . 
Meaning of the word marked with <WSD> tags:  a rate (usually rapid) at which something happens