Twisted pair's effect on power supply rise time
I assume you want the fast rise time to appear at the load on the end of the long cables. Or you have a high di/dt load and you want to minimize the voltage dip at the load.  In that case twisting the cables may help.  The magnetic fields of close conductors carrying opposite currents will tend to cancel, reducing the inductance associated with the cabling.  

The bigger the loop area between the two conductors the higher the inductance.  And since V=L*di/dt for a fast di/dt you want a small value of L (large V/L).