Thanks for your response.
I did a factory reset as well, but because I am a rookie on android I wondered if there are any typical background apps which are in 5.1 by default but not required.
Maybe removing even the smallest apps might improve performance?!
I use the standard Android browser, which is run by Fully Kiosk Browser (exclusively in Kiosk Mode - so no access to other functions without a password).
I am totally satisfied - however, the Xido itself could have more power, because it’s pretty slow.
I ordered a wall-mounted 10" tablet directly at the manufacturer in China, via Alibaba. The link is here:
It has a 10" IPS display with good quality (no spots or dead pixels), Android 6.0 rooted, a VESA mount with 75mm spacing, and can be powered either via a power adapter (included) or PoE (has a physical Fast Ethernet port). Multiple USB ports, a card reader, built-in speakers, no bloatware… There’s a built-in battery accessible through a panel in the back, a pair of 18650 cells which can be removed. Looks really good and works well. I can share more specific details for anyone interested, it’s still pending installation (the house is being completely renovated so it will be a couple of months). At 180ish USD including FedEx international courier and roughly one week from order to delivery, this was a really good deal with the extra features for permanent on-wall mounting + Ethernet + PoE that a regular portable tablet doesn’t have without extra accessories.
[Later edit] I bought a flat/compact VESA mount for it, made of two interlocking parts with V-shaped metal guides. One part stays on the wall, the other on the tablet, so it will also be possible to just pull the tablet up and detach it from the wall. (Obviously also unplug the Ethernet cable and enable wifi, it will run on battery for several hours.) Not sure why would anyone need to do that, but why limit the possibilities when the cost of VESA mount was the same