Roon uses different infrastructure on macOS vs Windows/Linux, and it comes with a scalability and performance penalty. This happens because Roon is built on Microsoft’s .NET technology and Microsoft has been very slow to bring .NET properly to the Mac.
Microsoft just released the first version of .NET that allows for desktop applications on macOS a little bit over a month ago, and we are working on moving Roon to their new stuff. When that is done, macOS performance should be just as good as Windows/Linux.
The effect of these infrastructure differences is much larger than i7 vs i9. Roon’s user experience is most influenced by single core performance, and i7 vs i9 is rarely more than a 10% difference from the same generation, and often much less.
I suspect that 32GB of RAM is enough for your library. 16GB probably is not. 64GB definitely is. Once you have enough RAM, extra doesn’t make much difference.
At that point, sure the slightly faster CPU will make a small difference. The real problem with running Roon on a laptop is that it will hog the resources of the laptop and have to compete with other software. On a dedicated machine, things are almost always more comfortable, even with slightly less hardware performance.