Take a look at your storage space in Settings - General - Usage - Storage. If there's not much of it left, this can slow down your device. Remove apps you don't use or need.
Delete old messages. They can be a reason for a slow Message app.
Restart your iPad - turn it off and on again.
Check your internet connection. Try a different one, maybe the one you're using is slow and needs updating.
To speed up Safari, you'll need to delete history, cookies and cache from time to time.