socket MSG_DONTROUTE option on local sockets

[devendra.aaru]

Hello,

If i use the MSG_DONTROUTE option on a local socket, i mean a tcp
socket (AF_INET or AF_INET6) with this option.
I know that first of all using the tcp AF_INET or INET6 is a dumb
decision instead of using the AF_UNIX family, but i have come to a
point where i couldn't change this as this code is legacy.

If i use the MSG_DONTROUTE option will that be a performance gain on
the sockets that communicate inside the system, not to outside? I am
guesssing that routing lookup performs once and then it will never.

for every packet there is no routing lookup performed so there wont'
be much gain in performance?

thanks,