Freezing after update to iOS 9.3.3
Try some basic steps:

First of all backup all data of your iPad and restore the iPad from the backup. If it still happens, restore the iPad to factory settings.

If that doesn't work, try downgrading to 9.3.2 (you can still do it) by downloading the IPSW file from ipsw.me and download the iOS 9.3.2 IPSW file for your iPad model.

If problem continues, you may have to take it to the Apple Store and let them service your iPad because it might be a hardware issue.