on mobile, its obvious that hw requirements are higher than described and still it isnt so instant as Win81 SL-based (AgCore + CoreCLR/Native) code. Trying to push UWP down to mobile devices is bad decision, although it simplifies something - finally its not working well. If I would be somewhere at Microsoft, I would as soon as possible revitalize Silverlight on mobile devices, at least on ARMs but why not on low-end x86 and build something like UWP but from bottom-to-up, to develop "mobile first" with possibility to upscale apps even on tablets or even full desktop, using native hw-accelerated Silverlight graphics engine (AgCore) also HERE AGAIN for windowed apps, with all the desktop power for CPU too, not pushing lowest energy consumption here too much as on smallest mobile phones. Windows8.1 SL-based UI/UX simply works well starting 2-core/1G SoCs so for sure on anything bigger must be perfect too; I did already device-restores to Win8.1 on the 4-core/1G phone, the 4-core/1G tablet and will do the same with the desktop... really; as on my current hardware AMD A8-3530MX/16G it is working "quite well" in Windows10, but I prefer to limit myself even for development still for Win8.1 base, on mobile and desktop. While on mobile, SL-based apps behave and look and feel better than near-to-UWP approach testable here.
It is something wrong in Microsoft state...