If you were to install MySQL on Windows and benchmark it, then wipe the system and install MySQL on Linux (on identical hardware), the Windows installation will always be slower. There is simply more overhead on Windows than on Linux, and Linux also has slightly better performance in some areas that are relevant to MySQL.
As for the exact amount of difference, you would need to test it for yourself, but I would say Windows would be ~10% slower depending on configuration.
Mike Hillyer, Technical Writer
MySQL AB, www.mysql.com
Office: +1 403-380-6535
Blog:
http://www.openwin.org/mike
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