TCP Loopback Fast Path allows Windows to bypass part of the IP stack if a certain IOCTL is set.

See https://blogs.technet.microsoft.com/wincat/2012/12/05/fast-tcp-loopback-performance-and-low-latency-with-windows-server-2012-tcp-loopback-fast-path/

AC: Put up a patch with TCP Loopback Fast Path enabled. Test it in Windows to compare the performance difference in a regular full Evergreen patch run. We're looking for time taken to complete a full patch here, to see if it makes a difference in our CI infrastructure. If there's no noticeable difference, we can close this ticket since we don't intend to prioritize Windows-only performance improvements for production.