When AMD unveiled its Zen 5-based Ryzen 9000 series desktop processors, it boasted an impressive 16 per cent IPC (instructions per clock/cycle) boost. This presented a significant opportunity for AMD, especially as its rival Intel grapples with CPU stability issues.
However, AMD appeared unable to seize the moment. The independent third-party tech media community largely felt that the Ryzen 9000 series' performance uplift was insufficient compared to the Zen 4-based Ryzen 7000 series CPUs, deeming it unworthy of a generational upgrade.
Comparative performance testing between Windows 11 24H2 and Linux (Nobara) revealed that the latter frequently outperformed in gaming and other workloads. It was speculated that Windows required further optimisation, a theory later confirmed by AMD. To circumvent the performance bug, the hidden Windows Admin account was used.
AMD had pledged to address the issue and has now disclosed further details about its forthcoming performance patch. The company asserts that Windows 11 24H2, in its current state, cannot fully use the broader branch prediction capabilities of the Zen 5 architecture.
Branch prediction in CPUs mitigates branch misprediction penalties and is particularly beneficial in highly pipelined processor designs.
AMD said that 'Zen 5' architecture incorporates a wider branch prediction capacity than prior 'Zen' generations.
“Our automated test methodology was run in 'Admin' mode which produced results that reflect branch prediction code optimisations not present in the version of Windows reviewers used to test Ryzen 9000 Series."
Optimised AMD-specific branch prediction code will be available in Windows 11, version 24H2 in preview through the Windows Insider Program (Release Preview Channel - Build 26100) or by downloading the ISO.
"Zen 5" will see the most significant boost, but this Windows update will improve performance for "Zen 4" and "Zen 3" as well. We're collaborating with Microsoft to roll out this optional update to all Windows 11 users soon.
AMD has provided examples of the anticipated improvements post-patch. Using a Ryzen 9950X, the company expects the most significant gain in Far Cry 6, with an uplift of 13 per cent. FC 6, being a single-thread heavy title, suggests users may experience notable single-core boosts. Cyberpunk 2077 and UL Procyon Office test also show respectable gains of seven per cent and six per cent, respectively.