In the case of the 15-inch Surface Book 2, it's the Core i7-8650U (quad-core, up to 4.2Ghz). The 13.5-inch model offers the same processor, along with one alternate option -- a 3.5GHz Core i7 from ...
The Microsoft Surface Laptop Studio 2 is Microsoft's replacement for the popular Surface Book laptops ... has a 13th Gen Intel Core i7 CPU, 16GB of RAM, a 512GB SSD, and Intel Iris Xe graphics.
2.8GHz or 3.1GHz, respectively). The processors are certainly powerful enough to handle a lot of multitasking, but there's more horsepower available through the Surface Book's processor options.