Reminds me of the Daily WTF one where a customer complained about the length of time a batch data processing operation was taking, so they optimised the hell out of the routine and did the same job in 1/100th the time, and charged them $x.

The customer decided that, obviously, something must be wrong since something that is doing so little work can't be accurate, how can they trust it? etc. So they added a delay 5, charged them an extra $x/4, and everybody was happy.

I'd try to find the link, but pretty much every Daily WTF article contains the same search terms...