My guess here,,, and I wanna stress GUESS is that the alcohol in the fuel is acting like the "dry gas" or "heet". The stuff ya put in the gas tank of your car if ya have water in the tank. This stuff is mostly alcohol and somehow encapsulates the water allowing it to be passed through the engine.
My guess on the RPM increase is the simple reduction of oil. If I run my concrete saw fuel 40/1 through my chainsaw which takes 32/1 My chainsaw will run noticably faster.