I always complained about people complaining about having lag and stutter, Because I never get it. I don't wanna say anything bad, but memory is usually the biggest issue. Some does have leaks, but due to the high amount of memory I got. I don't have to care for it, I think it's very playable and streamable which I did. But one thing I know that works. Decrease graphics to low or something then you can play without trouble.
I have 16gb of ram 1600hz, most of the games dont need more than 8gb.
If other demending games run smoothly and some doesnt than it can be a software issue or a bad driver issue usually a display driver.
I bought the gtx770 week after it came out, it took Nvidia about 4 months to release a proper driver for it.
Also many new games now run smooth after several patches, in the release notes it's also mentioned that the lagging or stuttering issues have been resloved for some setup's.