When I had more time on my hands, I was a big fan of customising the installation images for Windows XP and Windows Vista using nLite and vLite, respectively. Using these free programs, you can apply tweaks, remove components, slipstream updates and package up your favourite programs so every time you had to reinstall, a lot of the initial setup work was already taken care of. For Windows 8, there's WinReducer 8. While it's still in its infancy, it is being updated regularly.
As of the latest version, 0.32, you can remove unwanted accessories, fonts, drivers, languages, themes and services and enable tweaks to hide the Charms bar or show file extensions in Explorer (among many others), saving you trouble of applying these changes every fresh install. You can even configure the unattended install settings, if you'd like to cut that step out also.
While it's tempting to anything that looks even remotely unnecessary, it is possible to unintentionally break something, given how interrelated Windows' various components are. You're better off just gutting the obvious bloat -- ancient drivers, for example -- so that you don't end up with a crippled operating system.
The benefits of removing components probably won't manifest themselves as a performance boost, but Windows should install faster and you'll have extra disk space to play with, which can be at a premium if you're running your OS on an SSD.
Unfortunately, the app only seems to run on Windows 8, so you won't be able to use your current install of Windows 7 or older to configure the image beforehand. Though that isn't so bad -- you'll probably want to use Windows 8 for a while to figure out what you want to remove anyway.