Did a clean restoration to IOS 8.0.2 with iTunes yesterday. Safari on iPhone 5s running 8.0.2 is still considerably slower than our iPhone 5 running 7.1.2I always update through iTines and rarely have any trouble. I would bet most people who are having trouble do not update with iTunes.
Not a surprising question coming from someone with a 64GB iPhone. At least for me, doing the install OTA required at least 4.2GB of free disk space which I do not have and I refuse to get a higher capacity iPhone just so I can update the software via OTA.I only update through iTunes now if I have to restore my phone for some reason. Why do it when OTA works just fine?
try doing a real time comparison with safari on your iphone 5s to safari on an iphone 5 running 7.1.2 , it may show you performance issues. My iphone 5s runs safari slower than our three other iPhone 5 that are still on 7.1.2I did an "upgrade" on my iPhone 5s from iOS 7.1.2 via iTunes using the iOS 8.0 GM release back on September 9th and haven't had any performance or battery issues.