Howdy jeffd55
While the referenced article is a very good one, it does not address the key ideas in the OP [emphasis is mine]
I just updated my iPad to 9.2.1 and it now freezes on everything after about one minute. I deleted about 6 apps to free up space but this has not helped. this situation happened the last tiME i did an update too.
iPad 2, iOS 9.2.1, just updated
In your referenced article, at the end, it says (as many articles do)
Contact Apple Support to ...
...
It seems most relevant to search for [ ipad (or iPhone) freezes while in use ] where, if one filters out old threads, these are tops in discussions
These seem to be isolated to "some" folks - and - since they do not persist over time, they are dealt with by workarounds OR have been addressed by a further update (without fanfare)