I've been checking the rotation speed and wind and it definitely does go up and down on my (newest) IC2 exp build. Windmills drop down to standstill from time to time, as well as going up to more than x2 from average generation during storms.
How would you change the current winds to make the windmills more in line with other things? Because with current power generation of nearly 4 mil EU per unit of material used, it might actually be feasible to produce UU matter from gained EU, and have more than enough of it to craft new rotors...