Basic single-core scalar-only workloads of my own corroborate the grandparent, as well as most of the other benchmarks I've seen. My own 5600X is "only" about 50-60% better than my old Haswell i5-4950 (from Q2 '14) on this note.

But the scalar speed isn't everything, because you're often not bounded solely by retirement in isolation (the system, in aggregate, is an open one not a closed one.) Fatter caches and extraordinarily improved storage devices with lots of parallelism (even on a single core you can fire off a ton of asynchronous I/O at the device) make a huge difference here even for single-core workloads, because you can actually keep the core fed well enough to do work. So the cumulative improvement is even better in practice.

Now I’m curious, is this testing against some requirements for an application? Are they any applications that would benefit solely from scalar performance vs scalar, cache size, and memory speed.

Need to point out in particular that that best Haswell i5 was FASTER than the best i7 for single-core workloads, so this might be a factor in OP post.

And also that is the reason why I use such processor on my own computer, it was already "outdated" when I bought it, but since one of the things I like to do is play some simulation style games that rely heavily on single-core performance, I choose the fastest single-core CPU I could find without bankrupting myself. (the i5 4690k that with some squeezing can even be pushed past 4ghz, it is a beastly CPU this one)

Exactly. The only thing I used my system for that was really begging for more CPU was console emulation, and that depends more on single core performance than anything else.