The Retpoline enable on Windows 10 insider preview (191H) by default

Reference:

https://www.ghacks.net/2019/03/06/enable-retpoline-on-windows-10-1809-and-server-right-now/

https://betanews.com/2019/03/06/windows-10-performance-retpoline-spectre-fix/

https://www.bleepingcomputer.com/news/security/boost-windows-10-performance-with-retpoline-spectre-mitigation/

https://support.microsoft.com/en-us/help/4074629/understanding-the-output-of-get-speculationcontrolsettings-powershell

https://software.intel.com/security-software-guidance/insights/deep-dive-retpoline-branch-target-injection-mitigation

The Retpoline enable on Windows 10 insider preview (191H) by default