I doubt you will see any difference.
Depends; name resolution is part of the connection cycle, and given just how
often frontier obsessively connect/ tear-down/ reconnect (seriously, there is a connection sonata being played every time you move between instances) slow performing DNS will slow that cycle anytime the CDN sends connections to a new host (that the player's PC hasn't got an (unexpired) cached record for).
The game has both P2P as well as amazon centric (AWS) connections going on, constantly. So yeah, actually, a fast responding DNS helps anything doing connection gymnastics; which the Elite client sure does. I'm sure you're just trying to be constructive; but it's not quite that simple.
Note: DNS is simply resolution; therefore it'll impact how quickly a resource is resolved, so it can be connected to. This will have nothing to do with positional or general game performance, vis-a-vis ship movement. It may make instance changing a little snappier, as that's one of the times the client plays an opus tearing down and reconnecting to AWS.