My old Android tablet from 2012 had become so slow as to be unusable - I tried deleting apps, clearing caches and so on but it was hopeless. So I purchased a new Android tablet.
Trying to decide what to do with the old one, and having nothing to lose, I flashed it back to its original 2012 state: a somewhat scary process where you download tools and memory images to a PC, then hook the tablet up to the PC and use a combination of special button pushes on the tablet and PC commands.
Result was that the old tablet now runs great - I even did a couple of "normal" upgrades to move it up to where Android was in about 2014 without any speed penalty. I shall stop there though - I think it was the "upgrade" from KitKat (4.4) to Lollipop (5.0) and beyond that was the start of its original downfall.
The old one is now working so well that I regret buying the replacement tablet.
