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Comment by dvfjsdhgfv | Hacker News Reader

The wording re. the difference between Windows 10 and 7 seems intriguing:

> Windows 10 PCs with Haswell or older processors will see "more significant slowdowns" and Microsoft notes that a segment of customers may "notice a decrease in system performance”. > Windows 7 and Windows 8 PCs powered by Haswell or older processors will see a "decrease in system performance" for "most users".

Does it mean that if you care about performance, it's better to use Windows 7 instead of 10? It's not spelled out explicitly, but they way they worded it suggests so.

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The original post offers some more details on this matter:

> For context, on newer CPUs such as on Skylake and beyond, Intel has refined the instructions used to disable branch speculation to be more specific to indirect branches, reducing the overall performance penalty of the Spectre mitigation. Older versions of Windows have a larger performance impact because Windows 7 and Windows 8 have more user-kernel transitions because of legacy design decisions, such as all font rendering taking place in the kernel. We will publish data on benchmark performance in the weeks ahead.

Source: https://cloudblogs.microsoft.com/microsoftsecure/2018/01/09/...

It's the opposite way around. If you read it closely they say on windows 10, some customers may see a decrease in performance, but for windows 7, most customers will see a decrease.

An article in the verge states "Windows 7 and Windows 8 will be the worst hit simply because these older operating systems have features like kernel-level font rendering that will be impacted by the Spectre and Meltdown mitigations even further than Windows 10."

From the original blog release

> Older versions of Windows have a larger performance impact because Windows 7 and Windows 8 have more user-kernel transitions because of legacy design decisions, such as all font rendering taking place in the kernel. We will publish data on benchmark performance in the weeks ahead.

I interpreted it the opposite. Maybe someone can clarify. The question is why would there be a difference between Win7/8/10 - it's afterall the same WinNT kernel architecture and has the same HAL hardware abstraction layer, it's a matured software code base, so any fix should be possible on all supported versions in the same perfection.

Alternatively: It could be that Windows 10 has various performance optimisations that Windows 7 does not, and these have had to be undone as part of the fix.

In other words: If the fix would cause Windows 7 to lose X% performance, Windows 10 would lose that same X% plus any Y% advantage it had over Windows 7.

(This is just a guess, of course.)

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