GPS only works with WiFi
Basic GPS can take 12.5 minutes to get a first fix from a cold start. Yes, this is slow, which is why most systems are built with other features to speed up the time to first fix. 


With a data connection, your device will try to use assisted GPS to get a fix faster. Your device uses local infrastructure to learn which satellites are in view for the current location and corrections. The time to first fix can be reduced to seconds.  
With WiFi, normally the first location fix is based on WiFi location; your device queries a large global database for the MAC addresses of WiFi infrastructure and gets back a answer quickly. WiFi location accuracy is worse than GPS, but it is much faster. Once you have this WiFi position fix, it can be faster to get a GPS fix.