I’m sure there are horror stories about Intel configurations as well.
It’s 6 cores + HT = 12 threads total. Two threads per core.
Cubase is as far as I know not optimized for any CPU.
Be careful when getting a new Ryzen if you want compatibility with the next generation. Not all future Ryzen chips will run on any current or older motherboard as far as I know. Not a big deal, just make sure you double-check before buying.
PCIe 4.0 is nice, but I’m not sure you’ll benefit that much. Sure, you’ll likely get faster load times, but m.2 is already pretty fast. I wouldn’t go out of my way to get a Ryzen system just for that if you’re not doing pretty heavy work
Generally speaking, what puts stress on a single core on your CPU is a plugin or VST-instrument that needs to compute quickly so you don’t experience any latency when for example playing a note on a keyboard. This means that if you’re just mixing the demands are different from if you’re playing a keyboard for example, or singing and need realtime effects (assuming your interface can’t provide that).
So you should consider what you do and how you do it. If you have a long chain of plugins, meaning that you have one plugin after another in series - one long chain in one channel going to a group/output where you have another long chain - then you put a lot of stress on one core.
If on the other hand you spread the load in parallel with more plugins over parallel paths - meaning maybe just four per channel but with many more channels - then the load will spread over more cores and threads. When I mix for TV (post) that’s my situation. I have many channels and not that many plugins in series. It’s mostly in parallel. For me more cores/threads is better than a faster CPU, and I can always increase the buffer size if I run into problems.
I think you should also consider is how much power you need now and how much you’re going to need in the foreseeable future. It could be that if you get a 3300X you’re fine for a short amount of time, say a year, and then you have to upgrade. But at that point the 3300X is probably not worth much at all and so the question is what do you do? If you can’t sell it are you going to buy another “modest” CPU from the last generation? If you do that, would you maybe have been better off with a 3600 or 3700 from the start instead? You’d have to look at the loss from buying the 3300 + the cost of the new CPU, and if that’s more than the cost of a 3600/3700 today then you “lost” money.
Of course, if you don’t have the money you don’t have the money.
Lastly, just for the record: I don’t think I’ve read any reviews of anyone using quad cores for DAWs these days. Even hex cores are less common recommendations than octa-core CPUs. Not saying it won’t work, just that most people tend to get at least 6-8 cores (2x the threads).