after you grease those suckers if you realy want to get them to move quickly (and I mean nearly twice as fast)add a strong ground wire from the switches under the armrest directly to one of the ground wire bundles under the dash. or somewhere where there is a strong ground.
I don't remember the wiring exactly as its been a while since ive been in there, but I believe that the motors power AND ground leads go through the window switches; The switch simply reverses the direction of current flow in the motor.
If that's the case its probable that Alfa used a very thin ground wire which is by now corroded like crazy where it grounds to at the radiator support (or under steering wheel). Use a nice new 14 AWG or bigger wire directly from the switches' ground lead to a bolt on the chassis which you have verified to be a strong ground. This includes both the rear windows (on armrest) and the ones above your head (including the sunroof).