Google Nexus 7 2012, an excellent tablet, or at least it was until I upgraded the operating system to Android 5.x.x then it turned into an expensive paperweight.
It became useless, minutes to turn on, unresponsive apps. It had been rendered useless.
The only option appeared to be, implement a factory reset, but first, try this idea of clearing the cache.
I had not used my tablet since the beginning of the year. Long wait whilst 120 updates to apps.
I went through the procedure to clear the cache, then reboot.
One and a half minutes to reboot, similar sort of delay on the apps I tried. But this was probably because they were still requiring further updates, plus synchronising and updating messages
I ran CCleaner, Avira Antivirus and Optimiser.
Still around one and a half minutes to turn on, but all the apps I have tried, are now responding within a few seconds, and within the app, seconds more or less instant response when I tap.
This though does beg a big question: Why, when carrying out an upgrade, does Android not clear the cache then reboot?