I found an i7-7700K benchmark to compare it to [1]. Hopefully it's an apples-to-apples comparison...
[1] http://browser.geekbench.com/v4/cpu/compare/3036382?baseline...
[1] http://browser.geekbench.com/v4/cpu/compare/3036382?baseline...
That 90 watt part meanwhile is designed to put out that performance all day long.
(You might think that makes the iPad performance all the more impressive but that kind of throttling is nowadays built into the chip itself, it's not just limited thermal design. They are peddling this as a pro device and I would like my pro device to keep up that performance level for the entire time it takes to build my C++ project or run my deep learning kernel)