

Well, no need to websearch. Just go to the website and look for any official links, such as the wiki. As for the optimized packages, I found this on their website:
CachyOS does compile packages with the x86-64-v3, x86-64-v4 and Zen4 instruction set and LTO to provide a higher performance. Core packages also get PGO or BOLT optimization.
So the listed CPUs in the requirements list should take advantage of this I guess. And my assumption is, that these CPUs are required to run the packages at all. Maybe that’s where the “newer machines” is meant with.

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