Hi Chris,
We can address your concern by going to the Additional settings for your Surface Book's touchpad. You can adjust or increase the number of lines for the two-finger drag scrolling by following the steps below:
- Go to Settings and select Devices.
- On Devices, click/tap Touchpad.
- Scroll down and select Additional settings.
- Once the Mouse Properties box appears, click/tap on Wheel.
- Under Vertical scrolling, you may increase the number of lines to scroll at a time.
- Click/tap Apply then OK.
Let us know how it goes.
Regards.