I've asked a question in the same vein as this before, but I'm still looking to try and alleviate some of the issues I'm having playing simple games on my Surface Book.
I have an i7 / 16 GB / non-performance base model, and I don't do that much gaming. However, when I do try to, I notice that I get significantly lower game fps in fullscreen than in windowed mode, even if I reduce the resolution of games running significantly. For example, playing the Sonic 2 HD fan remake, I get a mostly-solid 60fps in windowed at 1080p; however, a full screen playthrough gives me 30fps or lower.

The same goes for playing this game and reducing Windows' display settings, the games' settings, or both to 1080p instead of 3000x2000.

Most of these games don't offer graphical settings more complex than resolution since they are 2D rather than 3D. Other 2D games I've noticed this in are ones such as Night in the Woods with a similar 60fps windowed / 30fps&under fullscreen, and even my own non-demanding game projects I build in Unity; I experience this with the Surface Book both plugged in and on battery. I have installed the NVIDIA Control Panel & GeForce Experience and all related drivers and tinkered with these to not much effect.

Any tips to get full screen performance to match as closely as possible to windowed?