Past AGESA change may lower gaming performance on Zen 4

[mackerel]

AMD Disables Zen 4’s Loop Buffer

A loop buffer sits at a CPU’s frontend, where it holds a small number of previously fetched instructions. Small loops can be contained within the loop buffer, after which they can be executed…

old.chipsandcheese.com

tldr: AMD disabled a loop buffer at some point between AGESA 1.0.0.6 and 1.2.0.2a. This tester observed ~5% perf drop when CP2077 (1080p medium, 6900 XT) was run on the non-3D cache chiplet of 7950X3D. No change using the 3D cache chiplet. Both CPU and GPU were fixed/limited on clock to aid consistency. No significant changes in SPEC benchmarks.

Other gens don't have this feature so will be unaffected. Speculation AMD may have found an edge case no one else has yet so turned it off to prevent hitting it.

Source is not a game tester so has no intent to follow up themselves.