safari is really slow on iPad 1, safari is really slow on iPad 1, safari is really slow on iPad 1

Try clearing Safari's cacheand history via Settings > Safari

If that doesn't work then try closing Safari completely and then re-open it : from the home screen (i.e. not with Safari 'open' on-screen) double-click the home button to bring up the taskbar, then press and hold any of the apps on the taskbar for a couple of seconds or so until they start shaking, then press the '-' in the top left of the Safari app to close it, and touch any part of the screen above the taskbar so as to stop the shaking and close the taskbar.

A third option is a reset : press and hold both the sleep and home buttons for about 10 to 15 seconds (ignore the red slider), after which the Apple logo should appear - you won't lose any content, it's the iPad equivalent of a reboot.

Or you can turn off JavaScript if you don't want to use YouTube. Also try and delete any unnecessary apps, that speeds up everything.