Question about IC propagation delay relationship to Vcc

[imperza]

Why does in the spec's sheet of an IC, the higher the Vcc supplied the lower the propagation delays output? I hope some can answer with theoretical knowledge. Thank you.

 

[crutschow]

In CMOS circuits, the higher the voltage, the lower the ON resistance of the transistors and thus the faster the various internal parasitic capacitances can be charged and discharged.