Hi, Tailscale person! If you want a fairly straightforward improvement you could make: Tailscale, by default uses SOCK_RAW. And having any raw socket listening at all hurts receive performance systemwide:

https://lore.kernel.org/all/CALCETrVJqj1JJmHJhMoZ3Fuj685Unf=...

It shouldn’t be particularly hard to port over the optimization that prevents this problem for SOCK_PACKET. I’ll get to it eventually (might be quite a while), but I only care about this because of Tailscale, and I don’t have a ton of bandwidth.