How do testers test focus speed?
It may be an impression of time from minimum focus to infinity.
This type of test has limited value if the minimum focus distances are not the same.
Most lens can "instantly" be made to focus significantly faster than from minimum focus to infinity
Just approximately pre focus and note the dramatic reduction in AF time to AF lock-on compared to minimum focus - infinity.
You have to be quick with a "fast focuser" like the Nikon 70-200 II.
Even my 200 f4 macro focuses fast used this way
Most pro sports photographers have their equipment pre-focussed on where they anticipate action happening: for the obvious reason this is the fastest way to focus lock on with any equipment.
For sports photography focus tracking ability is more important than minimum focus to infinity.
It is rare to see this tested, except with the bicycle rider camera body tests dpreview sometimes do. Even then the testers make the mistake (I presume it is a mistake they do not want to own up to) of using 3D focus tracking which Nikon clearly explain as being intended for side to side movement and not erratic travel toward the camera.
Some mention has been made of the more expensive news Nikon FL.
This comes with 4 AF on or AF-L buttons near the front of the lens which I much prefer to back button focus for sports action.
While there are no guarantees Nikon lens, new or second hand, usually depreciate more slowly than independent brands.
Put another way anybody who makes a purchase decision
solely on a test site AF speed/MTF may end up buying second best for their photography.
--
Leonard Shepherd
In lots of ways good photography is much more about how equipment is used rather than the equipment being used.