Hm. Not been my experience going back and forth between 10 and 11, but that's always the case with Windows, isn't it? Bit of a crapshoot in general.
Honestly, I have no idea how to evaluate real laptop performance these days. Most of the performance issues I have on battery devices are some unholy combination of horrific power management, bad software and semi-deliberate online weirdness with services throttling you out of adblocker spite.
People are out there telling you how well Youtube is meant to perform playing video and how long the battery is meant to run based on that and I don't even know what they mean anymore.