Let's say there is a 1km race, and here is the ranking:
A: 170 seconds
B: 301 seconds
C: 308 seconds
D: 312 seconds
We can say that A is fastest by a wide margin, because he was much faster than all other runners.
How to say fastest by a large margin in Japanese?
Adapting from ALC, I wrote
大幅に一番速い, but a Japanese colleague taught me that
一番 can not be used at the same time. She advised me to use only one or the other, but I feel that the idea I want to convey (much faster than all others) is lost.