While that sort of "time travel" is a popular way to speed up game play, real-time games rely on the accuracy of the computer's system clock to operate properly. Unpredictable results can occur if adjustments are made to the clock, especially moving the clock backwards in time.
While many people do adjust their system clocks to speed up play, doing so affects far more than just the games. Every application in your computer is affected, including the file system and Windows system applications. For all of those reasons, we do not recommend changing your computer's system clock to speed up game play.