Hey Steve,
Always great to hear your level headed observations. I still have not completely assessed performance with V17 and 10.4.10 as I'm currently finishing a project on another system that is on 10.4.8 (the latest versions were performing so slow that I had to downgrade).
Pretty much all of the issues you mentioned are what I experienced with 10.4.9. I still kind of noticed more spinning beach balls on my laptop system with V17 and 10.4.10.
The R3Ds at least play now and don't stall the software but everything just seems to make for a spinning beach ball moment that eventually makes me force quit.
I even noticed the lag issues on non RED projects with footage just using ProRes proxies.
I think Apple has been doing a lot of work under the hood (obviously with Metal but also perhaps more with the step to Apple Silicon) and it seems to be adversely effecting performance.
It almost reminds me of the many headaches people had going into Catalina (dubbed by some as the Windows Vista of OS X releases).
Perhaps despite changing the foundational code like METAL they may still need to optimize, not sure.
As much as I like Apple they seem to have an ass backwards way of implementing changes and not coordinating with 3rd parties (or perhaps themselves) when
doing so and I wonder if it's been biting them in the ass lately.
For now, I'm sticking to 10.4.8 as it was solid and it actually allows me to get work done.
I'm not sure how much of the issues is Apple, RED, or both but something clearly needs to get worked out on the latest FCP X versions.
Brian Timmons
BRITIM/MEDIA