Yesterday we done few 90 and 97 runs, there was aprox. 30 mobs with elites, we got lags that stops video for few seconds. It happend on more open maps and we had all 64bit version enabled.
Before recent patch I didnt had any lag issues (but I enable 32bit version cos 64bit was bugged).
So with 64bit, loading screens are instant, game looks better but now we having lag issues sometimes.
Here are few tips what you can try to improve game/network performance for Diablo 3