Laura Erickson's For the Birds

This powerful bird of prey has been clocked in stoops going faster than 200 miles per hour! Most specialize on ducks and shorebirds, but in cities can be adept at catching pigeons and gulls.

The Peregrine holds at least two records in the Guinness Book of World Records:

Peregrine Falcon: Fastest bird (diving). The fastest dive by a bird is that of a peregrine falcon (Falco peregrinus), which has been estimated at reaching a terminal velocity in ideal conditions of approximately 320 km/h (200 mph) when in a diving stoop hunting prey on the wing. Some experimental dives have suggested that even higher speeds are possible by this species, perhaps up to 389 km/h (242 mph).

and:

Peregrine Falcon: Keenest vision of a bird. It has been calculated that a large bird of prey has the keenest vision as it can detect a target object at a distance three or more times greater than that achieved by humans, and thus a peregrine falcon (Falco peregrinus) can spot a pigeon at a range of over 8 km (5 miles) under ideal conditions.

I’m not sure how the Guinness Book chose the Peregrine as having THE keenest vision compared with other birds of prey and other falcons specifically.