Ok a 12% differential on a LAN is kind of surprising. I wonder what Tailscale could possibly doing that would be causing this issue because aside from the control plane I don't believe they're in the data path all that much. Maybe WireGuard on Windows isn't as optimized as it is on Linux?

https://www.reddit.com/r/linux/comments/9bnowo/wireguard_ben... from 7 years ago is about trying to get it running at 10Gbps speeds.