I have used G2 and with all its power, it still lag/stutter a bit here and there. Though i am sure average user won't mind much, plus it makes up for it with excellent battery life and good screen to size ratio.
But since processing power is about same on G3, i can only imagine that stuttering would have gone worst now with QHD screen. And this time no more excellent battery life either to make up for it.
QHD might make sense with S805/S810 processors. Only time will tell.
Being an HTC user, i am not really used to any lags while doing simple stuff on my mobile so these micro stutters become a big annoyance over time.