That's a common problem in these appliances. Since it's just a tablet, why not factory reset and start fresh?
I have a Galaxy Tab 10.1 GT-P5100 - version 4.2.2 and have had it for about four years. It is being a nuisance by keep freezing and also being very slow loading the programme I want, eg, my daily paper I have downloaded, and sometimes I get a message saying the processor has stopped working. I got a message to say it couldn't update any Apps as the tablet was full, so had a look and realised I had used nearly 16 GB. I deleted some photos and Apps and it went down to under 15 GB but has crept up a bit again to just over. Could the fact that I have used a lot of the storage be making it freeze? I have lots of Google Apps that I haven't downloaded and don't know how to delete them and may not actually be able to. It is annoying as they keep updating.