Why does electric window on 1998 polo go slow when going up but ok going down only on near side?

Why does electric window on 1998 polo go slow when going up but ok going down only on near side?
Because when the window is going down it is aided by gravity and the motor doesnt have to actually do anything. Whereas it has to lift the windows full weight when going up. Try greasing the runners, this may get a little more life out of the motor.