Just from the power envelope (88W for the desktop vs 15 for the 8650u in the surface book 2, assuming it's configured to that setting -- edit: it is) the deskto

Just from the power envelope (88W for the desktop vs 15 for the 8650u in the surface book 2, assuming it's configured to that setting -- edit: it is) the desktop part would be 80% faster, if all things were equal. Now all things aren't equal. The mobile chip is going to be thermally limited, while a desktop chip has a huge heatsink and fan to it's service, and a lot of room to be "just warm". Despite whatever architecture improvements (and take those with a grain of salt, remember that skylake and its descendants are the most affected by the Spectre/Meltdown mitigations) you still have physics against you and the desktop part should be 50% faster simply because it can keep the turbos up and higher frequencies than a TDP-restrained mobile processor. It'd seem that, today, only the AMD Renoirs are capable of pulling "desktop-like performance on a mobile budget". Let's hope AMD keeps bringing good chips out, and Intel wakes up and stands with something decent, unlike what they've been doing so far. -- edit: Since I was already editing: of course a Ryzen whatever is going to be also TDP-limited compared against other Ryzens, but AMD isn't really making the mobile parts completely equivalent to the desktop parts. So yes, calling a Renoir "desktop performance" is massively ignoring AMD "super powerful" desktop chips. More reason to hope Intel gets up and starts giving a fight here. We need competition, otherwise AMD will turn the tables and will get back to a stagnant situation.