Lot of Apple users reported this issue. Slow YouTube download speeds on iPad, iPhone and iPod Touch.
This issue also happened for users who have strong WiFi or 3G signals. Other applications like Safari working fine but YouTube video buffering speed is very slow.
Solution 1 :- (Change DNS servers)
This make huge different in YouTube video streaming speed. Use OpenDNS.
Launch Settings app.
Tap WiFi option on the left hand side.
In your current WiFi network, tap blue arrow.
Tap the “DNS” field and enter the following DNS address.
After changing DNS, restart your iOS device (iPad, iPhone or iPod).
Note : If its does not work use Google DNS like 126.96.36.199, 188.8.131.52
Solution 2 :-
Close Apps that using internet in multitasking.
Use Jasmine – YouTube Client to watch the videos.
If you are using Safari like browser to watch YouTube videos instead of app, clear Safari cache.
Go to Settings -> Safari -> Clear cache.
Confirm that you want to clear the Safari cache. Now watch YouTube videos via safari.
If the DNS method doesn’t work, switch the wireless channel in your access point from o to 13. Restart your iPad or iPhone and check the YouTube speed.
Reset Network settings.
Go to Settings -> General -> Reset -> Reset Network Settings.