I did a factory reset and restored from iCloud. No idea how I ended up with 7 gb more free space though ...
Phone is now responsive on unlock again. Only annoyance if you unlock the phone and emails are coming in, you can't do anything with the phone until they are done (i.e. the background is not responsive and swiping the email up at the top does not help).
Phone is now responsive on unlock again. Only annoyance if you unlock the phone and emails are coming in, you can't do anything with the phone until they are done (i.e. the background is not responsive and swiping the email up at the top does not help).