Great read on bicycle tire pressure optimization along with the methods used to arrive at the result.
On the rough surface (rumble strip), our rider had to put out 290 Watts more than on the smooth surface (right next to the rumble strip). That means that 290 Watts were lost through vibrations of the bike and rider’s body.
After all this testing, we now can say with great certainty that increasing your tire pressure (beyond a certain point) does not make your bike faster on road surfaces that range from very rough to very smooth. In fact, on very rough road surfaces, higher pressures are a lot slower than lower pressures, because the suspension losses are so great. On most surfaces, tire pressure (beyond a certain point) simply doesn't make a difference in speed.