I'm using Windows 8 Enterprise on a quad core machine with 8GB of RAM. The performance is excellent and applications are launched amazingly fast. Even heavy ones, like Microsoft Visual Studio. That is until I decide to switch to Metro layout. Most metro apps are slow to launch. After the launch they are pretty fast and work smoothly. But loading the first screen takes at least 10 seconds. For instance if I click the Mail app icon, I have to wait at least 10 seconds to see my email list!
This video (posted by somebody else) explains the problem precisly.
The guy is opening a video using desktop Windows Media Player in the beginning. The video starts playing in milliseconds. The he tries to play it metro video player. In this case he has to wait more than 10 seconds until he can see the video playing.