Spectre and Meltdown are two security vulnerabilities in processors that were discovered some time ago, in 2017-2018. There are two variants of Spectre: CVE-2017-5753 (bounds check bypass, Spectre-V1, Spectre 1.0) and CVE-2017-5715 (branch target injection, Spectre-V2), both of which affect a large number of CPUs – x86 (Intel, AMD) but also ARM. CVE-2017-5754 was assigned to Meltdown and only affects Intel CPUs.
Software fixes have been implemented over time for all vulnerabilities. However, since the vulnerabilities exist in the hardware, they cause varying degrees of performance loss depending on the processor architecture. A very useful little program can be used to disable the “mitigations” or “workarounds” in Windows.
Why would you want to do that?
These mitigations can significantly reduce computing power, and it is highly unlikely that the security vulnerabilities will ever be exploited in a meaningful way in the private sector.
⧉ Toms HardwareTo squeeze a few percent more performance out of aging hardware running modern Windows (10/11), this is definitely a quick and sensible intervention. This is especially true when overclocking older processors, where every point in the benchmarks counts.
Switch off.
Gibson Research Corporation has released a super useful little program that allows you to quickly and easily get an overview of your current system and decide for yourself which mitigations you want to enable or disable.
You can download the tool here. The program must be run manually as an administrator. Modern processors have fixed the gaps in hardware, so there is no need for action. But the tool also reveals this information.
Field trial
The effects can be illustrated using the example of the Intel Core i7-7700K used in the previous “Küche PC” project. This was delidded, coated with liquid metal, and overclocked to the maximum. These comparison results were achieved under Windows 11 Professional 25H2:
| i7-7700K overclocked to maximum Spectre and Meltdown protection ON | i7-7700K overclocked to maximum Spectre and Meltdown protection OFF | Difference | |
|---|---|---|---|
| Cinebench R23 Single | 1423 | 1430 | + 0,49% |
| Cinebench R23 Multi | 7112 | 7191 | + 1,11% |
As you can see, the results are not earth-shattering, but they are measurable. Kaby Lake suffers less from mitigations than older generations before Skylake. “InSpectre” therefore also attests to “Performance: Good” with mitigations. It should not be forgotten that microcode updates also have an impact and cannot simply be switched off or circumvented.