Can someone explain to me what the point of an i7 (or even an i5) is on a laptop? Aside from speed? They all have dual core processors. It's not like the desktop lineup where each step up gets more cores.
Compare the i3-6100U to the i7-6500U - both skylake ultra-low-power CPUs [1]. The i7 has about 30% faster effective clock speed (plus the turbo boost, which gives a small jump in clock speed when necessary, which can reduce battery usage) and 25% more cache. But another i7 model, the i7-6550U, has better graphics, even faster turbo boost, and a bunch of "Pro" Intel features that neither of the others have. Move up to the i7-6700HQ and now you have two additional cores, incredibly faster performance, even more cache, and higher limits up the wazoo.
Of course, newer microarchitectures may have have more optimal code paths, slightly higher clocks, smaller dies, better graphics, and use less power. So an i5-7200U may have better performance, similar features, and use less power than an i7-6500U [2].
[1] http://cpu.userbenchmark.com/Compare/Intel-Core-i3-6100U-vs-... [2] http://cpu.userbenchmark.com/Compare/Intel-Core-i5-7200U-vs-...
https://en.wikipedia.org/wiki/List_of_Intel_Core_i7_micropro...
Also not really applicable to this review, but if you want a machine with say 32gb of RAM, that requires a bit higher of a processor.
And some laptops do come with more cores — my 2014 Thinkpad has 4.
You can get 4 core CPUs in larger laptops where the i5 is 4 core, 4 thread and i7 4/8. Similar to desktops.
I don't know what you mean - my pretty old laptop has an i7 with four cores and eight threads - an I7-4870HQ.