It will route directly over the local network when possible. It will be encrypted through the VPN, so there will be some overhead. But will be as direct as it

It will route directly over the local network when possible. It will be encrypted through the VPN, so there will be some overhead. But will be as direct as it can be. It only routes through tailscales servers as a last resort, when it can’t find a direct route at all (usually because NAT holepunching fails somehow). Their “DERP” relay servers just relay the encrypted connection. I think you can use your own relay servers, but I don’t know if that feature can be disabled entirely. Headscale can be entirely self-hosted. It still uses the tailscale client applications- but is compatible.