ModernUI Tuner is a app which created specially for WIndows 8.1 Update 1, Spring Update, Feature Pack, or how it is called there. It can control several secret hidden options of the "Update 1" and will make your Windows a bit tunable and flexible.
In short, with ModernUI Tuner you will be able:
to speed up Metro apps closing with mouse
to speed up Metro apps closing with touch gestures
to speed up the "flip to close" feature.
to change the Switcher (top left corner) hover timeout delay separately for Desktop and Modern apps.
to change the Charms bar hover timeout delay separately for Desktop and Modern apps.
to disable the shutdown button on the Start Screen
ModernUI Tuner is a free, portable application. It works on Windows 8.1 Update 1 x86 and x64, no separate x64 version is required.