DSP is mostly single-threaded per zone (there are exceptions for DSD, and multiple zones can use multiple threads). However, if you have a multiplier of 21 times in signal path, your conclusion of single-threaded DSP being your performance bottleneck is way off. That number is explicitly telling you that less than 5% of your CPU is being used on DSP. If you were bottlenecked, that number would be closer to a multiplier or 1 or even lower than 1.
I don’t know enough about what you were playing (format), to what (endpoint), from where (source of content), in what manner (DSP, zone settings, MQA stuff, etc…) to make an educated guess on why you were stuttering, but if I’m correct in assessing that you are using an M1 Macbook with Rosetta, there is no way it was DSP (unless you had something like DSD512 going with crazy number-of-taps convolution filters).
It’ll happen. There isn’t a performance issue here at all with Rosetta, so we’ve not prioritized this to the front burner.
We need Apple’s support to do this. There are many threads on this site about the topic. I’m not going to awaken this idea here, so I’ll just leave it at that.
I’m glad you are enjoying Roon. It’d be good to figure out your stuttering in a Support topic, and the rest is on the radar.