I see what you are saying and yes there is a genetic element BUT say a pup goes to a working home, used on hares successfully, very fast, if that same dog went to a pet home and was never trained for running it would not achieve the speed it would in a working home
Depends what you mean by "faster" Ultimate top speed or timed over a given distance?
Given a reasonable degree of fitness, (not talking about a fat lump of lard here) the pet dog probably would reach the same TOP speed, but wouldn't be able to sustain it for the amount of time the fitter working dog could. IMHO.
I ag