"Lag" when using big region target selectors (dx, dy and dz)

The bug

If in the region target selectors, @something[x=X,y=Y,z=Z,dx=DX,dy=DY,dz=DZ], you put big DX, DY, and DZ values, Minecraft hangs.
For example, doing "/say @e[x=-50000,y=0,z=-50000,dx=100000,dy=256,dz=100000]" causes the game to hang. This isn't noticeable in gameplay, but only when you try to send somewhat in chat or to close the world.

Affects: @e, @r[type=!Player]

Code analysis

Code analysis by AjaxGb can be found in this comment.