One issue that I've run into many times that doesn't seem to have a 100% solid fix is dealing with the really slow loading of YouTube videos using the native YouTube app on iPhones, iPads and iPod Touches. Sometimes it's really slow over a WiFi connection but it will work fine on the much slower 3G connection. Seems backwards. The theory is that the native YouTube app is pulling in whatever the highest quality HD version of that particular video is - so it might be loading a very large 720p or 1080p video, which can take some time.
One workaround is to skip the native YouTube app provided by Apple and instead use the m.youtube.com mobile site. The site defaults to "high quality" but doesn't pull in the really large HD versions of videos so it loads faster in theory. Plus it has some nice searching and sorting features that are not present in the native app.
As far as fixing the native app, I've tried all sort of suggestions. One popular suggestion is to change the DNS servers that your WiFi connection is using. People have suggested using Google's DNS servers (220.127.116.11 and 18.104.22.168) or some other DNS provider like OpenDNS. I've also seen people recommend changing channels on your WiFi router or disabling Wireless N and only using Wireless G networks, but there is no way I'm turning off Wireless N just to get some dumb videos to load faster!
But the one thing that DOES seem to work for me is to clear the cache for your Safari browser. I'm not sure how this is related to slow loading YouTube videos but it does work for me most of the time - at least better than any other fixes I've tried.
How to clear your Safari cache:
- Go to Settings app
- Scroll down and click on Safari
- Click on Clear Cache
- Confirm that you want to Clear Cache on next window
Update! : In the latest version of iOS, it seems that the "Clear Cache" button doesn't exist now so you need to hit "Clear Cookies and Data" instead.
Now try your YouTube videos and see if they load any faster. If it's not working immediately, you might want to trying forcing the YouTube app and/or Safari app to close. (Double-click home button to bring up running apps list. Hold finger on Youtube or Safari until it starts to wiggle. Hit the red X to kill it.) Or you could also try rebooting the phone.
I hope this helps! Please comment if it works for you. Or do me a favor and click on an ad or two. :)