lol, thats halarious. i dust my pc every 2 weeks, cause i live in the desert. gets pretty bad, in just 2 weeks time, i can run my finger acrost the bottom of my case and pick up about enough dust to halfway fill a pepsi bottle cap. and it does increase my preformance, i run 3dmark before and after i clean, before i got like 980max, and after i got 1100+(same hardware config, no software changes, just turned off, blew out, cleaned fans, and turned back on)
and temps went from 20c idle and 30c load to 18c idle and 25 load. even tho i realy dont need a fan, i ran with out one for like 3 days and the max temp was only 45c, and this thing can handle 85c. lol
and for the whole, you clean your engine, it will go faster, err, yea. if you clean the pully's, serpintine belts, fan, and clean the radiator, new oil, antifreeze, and tranny fluid, clean driveshaft, and balance tires, it will go faster, or atleast accelerate faster.( not notaceable, but its there, same with pc's, not noicable, but its there)
now for shower...you would run the same speed but not for as long because you would get hot faster then slow down, and you wouldnt realy run that long anyways, because i imagine if you dont take a shower for any longer than 2 days, you must have horrible hygene.
just for the heck of it, for xmas im gonna get 2 of the exact same pc's, and clean one every other week, and never clean the other, and just let them run for like 6 months, then reinstall the os on both pc's and 3dmark em. bet the clean pc would have better preformance and cooler temps.