The problem has a few symptoms. 1) Whenever I return to the home screen it takes a few seconds to redraw. 2) Most applications restart when I switch back and forth between them. 3) If I go to the Running Apps menu many of the apps are listed as "Restarting". 4) Some background applications quit unexpectedly (like playing music in the background).
This is on a Moto G Android v4.4.4. The phone is a few months old and the problem appeared about a month ago. At all times free RAM is ~200 MB out of 870 MB.
Could anyone give me some hints of what is going on? The Internet tells me to factory reset my phone, but that's a bit of the "Reformat your C:" of the PC world back in the day.