I doubt it. Seems like a 10.0 project.
I think the lag will diminish as people finish the patch and stop playing, but I know there would probably be just as much lag in 9.2/10.0.
Lag where?
Maybe think of updating your PC or turning down settings? You are probably confusing lag with FPS drops. Other then that check your network.
Everything has been smooth as butter other than world bosses but those are always laggy.
Give it a month or two and we be back to empty servers, no more lag 
Yesterday in maw, 6ms, 104+ fps, gtx 3090, I was playing as if I was on 4000ms, whole general chat was in flames about lag.
Idk when they will ever fix the lag or optimize the servers so it’s enjoyable to play but there is no lag in Alpha phase 1 of Ashes in a full raid.
The lag gets pretty bad in the maw and Korthia when the world boss is up. Blizzard servers have trouble with more than 5 spell graphics in a small area.