After testing more than 20 laptops with Whiskey Lake-U processors, the raw gen-to-gen performance advantage looks to be one of the smallest in recent years. If you own a Kaby Lake-R laptop, it may be best to hold off on buying a replacement until Ice Lake comes out later this year.
https://www.notebookcheck.net/The-average-Whiskey-Lake-U-laptop-is-just-8-percent-faster-than-Kaby-Lake-R.409376.0.html
it uses much less power.... especially for new laptop display technology. 14nm++ keeps it faster, maybe gpu has a bump here. 10% is not nothing, too//
Sorry, but there is a *big* difference: Whiskey Lake 'fixes' Meltdown - thus does not need either KVA shadow nor L1TF flush - mitigations that can have *big* impact in some workloads. Similar to Coffeelake-R.
Unfortunately like Skylake/Kabylake, Whiskey it is not able to use Retpoline (at least the standard version) thus IBRS/IBPB are needed for Spectre 2 kernel transitions. As Haswell/Broadwell (and earlier) can use Retpoline they may end up faster in some workloads than Skylake/Kabylake/Coffeelake - a ridiculous state of affairs.
I'd say only buy Whiskey Lake and *not* any of the older ones unless they are massively discounted. If buying now at all.
You can feel the responsiveness of the system with the mitigations on/off so the older systems 'feel' sluggish even on raw compute workloads you may not see a difference. But if you benchmark responsiveness that involve user/kernel treansitions the difference can be large.