As far as I can tell, the Windows Camera app in Win 10 pretty much *IS* a relabelled Lumia Camera. All I know is that it launches quickly and smoothly for me on my L 830, focuses like it's supposed to and doesn't really hang during normal camera operation. YMMV, depending on what version firmware you have (NO, not the OS version; the FIRMWARE) and perhaps on whether or not you've done a hard reset and rebuilt your OS install from scratch. If your Win 10 OS install turns out wonky, you might want to plug your phone into WDRT, see if there's a firmware update available and then update/rebuild from scratch accordingly...