Just a heads up on something I've noticed. Some lock screen apps are causing lag, loading screens and restarts.
I have "Dynamic Wallpaper" and while this app hasn't caused any system issues, it did mysteriously stop working. So I downloaded some apps that I have used previously with 8.1, "Lockie" & "Lockmix", both caused system problems like lag, loading screens and restarts immediately after install. Those issues also immediately stopped after uninstalling the apps.
I'd imagine that there are many other lock screen apps that were developed for WP8 that will cause similar issues, so if your having these problems I'd suggest trying to uninstall these type of apps first.
BTW, I'm using a Lumia 950.
I have "Dynamic Wallpaper" and while this app hasn't caused any system issues, it did mysteriously stop working. So I downloaded some apps that I have used previously with 8.1, "Lockie" & "Lockmix", both caused system problems like lag, loading screens and restarts immediately after install. Those issues also immediately stopped after uninstalling the apps.
I'd imagine that there are many other lock screen apps that were developed for WP8 that will cause similar issues, so if your having these problems I'd suggest trying to uninstall these type of apps first.
BTW, I'm using a Lumia 950.