iPad got slow, missing drive space I got an iPad 4th gen from 2012 with 16 GB space. It's in use daily.

For a few months now we have seen the iPad becoming more and more slow. Like, the Safari browser doesn't get up in under 10 seconds.

Also, when I start a game the game crashes saying "no space left on device". But in reality, there is more than 1 GB left.

I believe my flash drive is somehow broken. It shows me a total capacity of 13,05 GB instead of 16. I know, you may never see the full size, but missing 3 gigs feels a bit much.

Any ideas what I can do with this iPad to make it work nicely again or at least analyze what is going on?
Part of the 16GB is taken up by iOS. The system usage screen won't show a category for the OS itself because there's nothing you can do about it.

Your device is coming up on about five years old. Modern device will perform much better on a more resource intensive OS. You could try a restore but really I think it's just that the new features and technologies aren't well optimized or are simply too much for it.