iPhone 4S before upgrades I have upgraded my iPhone 4S to the iOS 8.0 version and it has made my phone extremely slow. Can I restore my iPhone 4S to its original state before any upgrades were done?
Short answer - 'No'

Apple stopped signing iOS 7 in Sept 2014 for any device capable of running iOS 8.

There is no going back, even if you have a legitimately downloaded ipsw file for iOS 7, as it will never validate.