Performance tip - Disable Spectre/Meltdown security patch

OK, first of all… I didn’t do any specific benchmarking with and without this performance “fix”… but from general experience, I think it is really significant.

Intel CPUs suffered from a side channel security issue known as Spectre/Meltdown which was discovered a few years back. In response, changes were made in Windows and in CPU microcode. All of these changes cost performance… how much, you be the judge. For reference:

The nature of the security issue is very esoteric and quite difficult to exploit outside of lab conditions. For me, my choice is to take the risk and leave the vulnerability unpatched and get my performance back.

This can be done largely by adding the following two Windows registry keys:

reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management” /v FeatureSettingsOverride /t REG_DWORD /d 3 /f

reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management” /v FeatureSettingsOverrideMask /t REG_DWORD /d 3 /f

Simply execute each of those command lines from CMD.EXE running with admin privilege. Reboot… see what happens to your Cantabile performance. I think it made a significant difference for me (again, I didn’t bother with specific benchmarking).

I think it will depend on what CPU you have, how much it will matter. I have a Core I7 8750H, FWIW.

I’m interested to hear if you try this, and if you notice significant improvement in Cantabile performance.

Patches to mitigate these issues have been released over the years via Windows Update and BIOS updates.
Anyway, they refer to attacks that are possible with systems that are tricky to implement, in some cases only having physical access to the PC (on PCI bus or Thunderbolt).
So, I don’t worry much about that. My personal mitigation method is to keep the PC cut off from the Internet, unless strictly necessary (software activation, important upgrades, etc).

Regarding the lost speed due the patches, I have never verified. From what I read it’s close to 10%.

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For the records, I tried the “perftest” before and after apply registry commands.
Same result.

For those older computers the performance hit was 5-10 percent. On newer computers you probably wouldn’t see a difference. In 2018 we saw performance hits after the initial patches were rolled out by Microsoft.

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