Routing between two interfaces on the same NIC takes nanoseconds. You wouldn’t notice a performance difference.

When I first set it up, I didn’t have a static IP address, so it would not be great when it changed. I also want my server to remain reachable locally if my internet goes down. I had different firewall/ACL rules for wifi too. For example, some of my internal websites only prompt for a login if you’re outside the network.

IPv6 has been awesome here. I have my server and clients on different /64 subnets in the same /48 block. The nearby devices on Android assumes only the same /64 is local.