One and only one of them has an odd performance problem that I almost-remember reading about somewhere a while back, maybe regarding an optimization or something related. I’m hoping someone else might remember same or know the solution.
System caches have been flushed. Any other apps are shared on both. Restarts, "optimize", etc., it’s all been done. In Developer options, I enabled "Pointer Location" to demonstrate what’s happening. Please see pics.
On both tablets, I performed a simple slow touch then swipe right to left. The result is completely repeatable and consistent, so it’s not a variation in my touch. The first pic, from the first purchase, shows a steady almost continuous red line made from dots indicating the motion and sampling thereof. The second pic, from the second purchase, shows the problem clearly: the touch is met with a low sampling rate period that then "ramps up" to match what it should be (and is on the other tablet). I am guessing this is some sort of optimization, but who knows. Apparently the hardware and software (assuming no defects) are not the issue, as the tablets are otherwise identical. So maybe it’s a setting that can be changed.
This performance issue shows readily in anything from scrolling home pages (I did try tweaking the suggested options regarding this; it had no benefit) up to Minecraft — which otherwise runs great, but when press-and-holding to mine, then turning to move to another block, the second tablet chugs like no one’s business.
Sorry about posting pics this way; this particular form didn’t appear to support any other method.
Second tablet (with problem)