比其他人要快五倍 = This means: SIX times faster
1. X倍(快) is adj. =X times faster
2. 快X倍 is comparison word= X+1 times
ex:
我是你的2倍=我是你的2倍快=2 times faster=twice as fast as you
我大你2倍=我比你快2倍=我快了2倍=3 times faster/bigger
**if we have the same speed (I am as fast as you), we won't say '我是你的一倍快' we will say '我跟你一樣快' most of time.
so when people say 我是你的一倍快, we will directly see as '2 times faster'.