In terms of the audio itself, meaning the VSTi, recording, mixing etc, it’ll either work or it won’t. By that I mean that if it doesn’t work and you run out of CPU resources you typically get clear indications of it; clicks, pops or whatever. So when that’s the case either more cores or a faster CPU will typically help.
Since the new Ryzen CPUs came out I’ve followed testing again since I might assemble a new computer, and what I’ve seen is that there seems to be slightly different results depending on how you load the CPU. If you’re purely mixing you can increase the buffer size since there’s no practical difference to the operator (you) between 64 samples and 256 samples, and when you do this you can benefit greatly from having many cores. When you drop the buffer to record however it seems speed is king, and you benefit more by having a faster CPU.
Lastly, I think the argument can also be made that the CPU not only has to deal with your DAW’s handling of audio but also many other things that go on in your computer at the same time. So I think there’s probably an argument to be made for more cores making for a smoother experience in many cases, simply because you can allow yourself the convenience of having a browser open or whatever at the same time without any issues. This is a hunch of mine and I haven’t tested it, and neither has anyone else in pro-audio as far as I’m aware, but it holds true in gaming for example where gamers want a great gaming experience while streaming video of them actually playing. More cores help there.
I think it is, but I also think that you probably don’t see differences between every generation. Instead I can imagine that between versions maybe a decade ago perhaps Steinberg tweaked something. Similarly, if ASIO-Guard changes something when it comes to threading or efficiency or whatever that may make for some different results. I wouldn’t worry about it though. If you’re in the market for a new computer it’s probably most cost efficient to buy either the low end in which case you’ll have problems no matter what, or aim for just below the high end, and then in many cases you’ll have enough power for a few generations of the software, unless you’re always pushing it to the edge of course.