Why does it spinning on a wifi Air 2

Reset your device: hold down the home button along with the sleep/wake button until the screen goes black and you see the Apple, then let go. (No data loss)

Copied it from Google. Another user said it worked.

Seems more like a problem with a slow/poor internet connection or WiFi interference. Try the Speedtest app.

This is one of things that just happens and it's hard to pin down why. Sure, the wifi connection itself could be doing it but I've seen it here and there even though the page has completely loaded and there shouldn't even be any activity.

The thing for me is that it doesn't affect the browsing experience or slow me down so for the rare occasions it happens I just chalk it up to "oh well".

Don't fret it unless you really start having problems because of it.