It generally took officials about 15 seconds to get the ball spotted to start the play clock under the old rules (and it wouldn't have been any quicker with ECU players taking their time getting up if the old rules were still in effect). Changing from a 25-second clock to a 40-second clock has no effect on the game. The rule that will shorten the game somewhat is the starting the clock when the ball is spotted on out of bounds plays. But since that won't happen in the last 2 minutes of a half, we'll barely notice it.
BTW, I was glad to see ECU come back to win after almost losing the game to the dumbest rule in football, the 2-point "conversion" after giving up a touchdown.