Wifi is fixed if you do this, but I admit it's not the *complete* fix.
The fix for my iPhone 5s (and my wife's new iPhone 6) is the following:
Settings -> Privacy -> Location Services -> System Services -> Wi-Fi Networking -> Turn OFF.
This setting left on just uses your WiFi as a helper for GPS location to get a faster fix (from what I read), so for now at least - turn it off. Doing so has completely addressed my WiFi issues.
Didn't help mine at all. Slooooooooow