Not really. You more than likely wouldn't even see it on all but the best dynamometers. Also, taking off the air pump only frees up about 1-1.5 HP, so if you noticed a difference after removing it......look for power elsewhere, I think you're wasting your time worrying about the belt. Now, underdrive pulleys are a totally different ballgame.
Get manual steering and ditch the entire a/c system if you're serious about losing parasitic drag. If you drive this car every day, I wouldn't do it.