Your PC is too fast. Get a slower one. Srs.
Your GPU will speed-step as needed only to do what it needs to do. If running the game at 600 fps is not enough to push it past it's first setting, then it's gonna lag because it's a high end gaming card - not designed to run smoothly at low clock settings. This is the part where you actually helped ME before. By setting my FPS to unlimited, my GPU clock ran at peak performance (frame limited by MSI Afterburner) and the lag was gone. Perfect smoothness. If I limited it any other way, my GPU clock would drop to a lower setting to save itself, and I would get frame lag. Temp only tops out at 55C while playing anyway so there's no problem doing that.
Speed-stepped lower clock settings = lag.
Noone said anything about sound cards. Although most people know about the delay already, because it is mentioned in just about every review, and that creative has bad drivers. Asus seems to be doing better, but I'm still not convinced to actually buy one. Current day realtek onboard sound is 192KHz/24bit, 97dB SNR with a headphone amp (on my board). As far as I'm concerned, this is fine.