I just bought a SB with the Performance Base. i7/16gb/512/dGPU. From the moment I started using it UI performance has been awful. With nothing going on but a couple of open idle apps all Win10 animations, such as opening the overview of open windows, switching desktops, etc is slow and laggy. I can't figure out how to measure FPS outside of a game but it seems like FPS for Windows is probably 15-20 fps. The worst is seen when using virtual desktops. After switching desktops any UWP apps will lag or hang for second, they'll redraw, resize elements (as though desktop scaling changed) or the cursor will turn into the blue loading circle.
This system is around 24 hours old and is basically stock. I've only installed 2 Win32 apps; everything else is from the store. I've installed all updates including Creators. The only "weird" thing I've done is install the display driver from Nvidia, but I only did that in the course of troubleshooting and it had no effect one way or the other. CPU is basically idle, nothing is going on in the background.
This system is around 24 hours old and is basically stock. I've only installed 2 Win32 apps; everything else is from the store. I've installed all updates including Creators. The only "weird" thing I've done is install the display driver from Nvidia, but I only did that in the course of troubleshooting and it had no effect one way or the other. CPU is basically idle, nothing is going on in the background.