Not exactly premature optimisation - but certainly misguided - this was read on the BBC website, from an article discussing Windows 7.
Mr Curran said that the Microsoft Windows team had been poring over every aspect of the operating system to make improvements.
"We were able to shave 400 milliseconds off the shutdown time by slightly trimming the WAV file shutdown music.
Now, I haven't tried Windows 7 yet, so I might be wrong, but I'm willing to bet that there are other issues in there that are more important than how long it takes to shut-down. After all, once I see the 'Shutting down Windows' message, the monitor is turned off and I'm walking away - how does that 400 milliseconds benefit me?