I and a lot of others unfortunately are in that situation. I think the optimization for 64 bit systems was done by a cack handed three year old with one thumb and two fingers missing on both hands. Symptoms: the Launcher, once you click on it, shows a message stating "Applying non-critical updates. This will take some time", and a progress bar in green that never gets to the end. In Process Monitor it shows that the Launcher is in some inifinite loop mode trying to sort out the Sound Cache files. If I click on the Play button and follow the log-in procedure to get into teh game, there are multiple instances of lag spikes and freezes in the game client. My character can do high-numbered hits on an attack and I can move him about for several seconds before the numbers flash on the screen to show how badly the character has mullered whatever he hits, then things get back into real time System is a Windows 7 Home Premium, in 64-bit mode, new install on all new hardware. Foxconn Flaming Blade motherboard with the Intel X58 chipset, updated to latest bios Hitachi Deskstar 250 Gb disk 6Gb of OCZ Gold Edition DDR3 RAM HIS branded AMD HD6870. In fact, it is three times as good as the recommended specs for the game according to the Windows 7 spec checker included in the Game Explorer folder, yet it still runs as if it has one leg tied behind its back and with blinkers on. Any ideas of what is causing this problem, as Blizzard do not seem to have a clue, at least none of which they are putting up on their Technical Support forum pages.