Originally posted by Stavri AF performance is really hard to measure precisely,
Indeed. It's often really hard to just start from a level playing field with lens AF performance and speed tests. Especially if comparing lenses across systems, since you will never be able to mount a Canon 70-200 f2.8 L on a K-3 to test its AF speed against the Pentax 70-200, for example.
You can do it by at least running different but comparable K-mount lenses on the same body with the same AF settings (eg the Sigma 70-200 OS vs the Pentax 70-200 on a K-3), then measuring time to AF confirm on a standard target, time to cycle fully from MFD to infinity etc etc. But they didn't attempt that at ePhotozine.