It's better than indicated in GP, but as an indicator of how good modern CPUs are in comparison to older ones, this page page overstates the case. The older CPU is 4-core but 8-thread (hyperthreads), the newer one is 8-core and 8-thread (no hyperthreads). The multi-core benchmarks are much higher for the newer CPU because it has twice as many cores, so that is inflating the overall score quite a bit. That said, it's not as simple as halving that score, as hyperthreads don't scale quite the same way, so it depends on how the multi-core test is formulated.

Edit: Oh, wow, as taspeotis points out it's not even the same two CPUs in the original Intel Ark comparison (which I was working off of from memory when noting cores and threads). The i9-9700k is actually an 8-core and 16-thread (hyperthreads) CPU, so it is actually literally twice as many cores and threads. It's still better performance, but not nearly as lopsided as it even seemed before, given those resources.

GP said “I'm comparing the i7 here to the i7 in my current computer” and you linked to an i9 vs i7 comparison...

53% single core clock improvement over almost 8 years.

Transistor count has increased from 1B to about 7B, which is roughly in line with Moore's law though...