Performance Increases
Microsoft knows your fears, and has addressed them: Windows 8 is slated to have better performance than Windows 7, even with this metro interface running on top of a desktop. We ran a few tests back when the the Developer Preview came out and found that to be the case, especially when it comes to boot times. Tablet users and netbook users especially should notice a fairly significant performance increase with Windows 8. Especially considering that any of your tablet-based apps will suspend themselves when you jump into the traditional desktop, so all they take up is a little of that extra RAM.