Blocks break faster at a distance

Blocks appear to be breaking faster when mined at distances, around 2x as fast.

Noticed when using Efficiency 4 (plus fortune 3, mending, unbreaking 3) diamond pickaxe and mining deep slate.

To recreate experience, stand as far from target blocks as possible while still having them in range to be broken, hold the break button down with the pickaxe selected and move sideways. In this configuration the blocks break apparently instantly, and almost twice as fast as when the target blocks are directly in front of the player (less than 1 block away).