Eleazyair

The OS lag, more to do with the dual core CPU. The SB is more of a Ultrabook then a pro grade laptop.

That's normal. Even though you are using the dGPU, PS is still ridiculously CPU intensive. Expect the SB and SP4 to get warm on the screen when drawing on it.

I would recommend a dBrand skin for the base of your SB to prevent scratching.