Another cap wearing guy, I always wear a clean Pace skull cap (I have half a dozen, I also wear them under warm winter hats). It is impressive how much this saves the helmet pads. Straps are my limiting factor.

When I wash helmets, I fill the bathroom sink with water and a little laundry detergent. Get the whole helmet wet, squeezing soapy water into the pads. Then I flip the helmet over so the straps soak and go do something else. Later I rinse, squeezing more fresh water through the pads and doing a good rinse on the straps. Doesn't take very long.

Edit: Last step is to press the pads with a towel.

Ben