MCClock

1) Run Minecraft 2) Run MCClock 3) Right-click on the taskbar icon, and click 'Enable' To change speed, right-click on the taskbar icon, and hover over 'Set speed multiplier.' A list will pop up, showing all the current speeds. When finished using, make sure to click 'Synchronize Time' and choose one of the options. This will reset your computer time back to the correct time.