Lenovo Y50 laptop stutter/lag?

Okay so I'm not really a laptop guy. I normally use a desktop. But recently I got this Lenovo laptop which a lot of people says it's "pretty decent" for gaming. Therefore I tried running games like GTA 5. I set the graphics to mid-range and it will stutter. So I tried low setting. It also stutter… I even tried playing games that my geforce gt 630 can handle at max graphics, it also stutter. It's like the whole screen will freeze for a second or two. Is there something wrong with my laptop?!

Spec: Intel i7 4710HQ @ 2.50GHz
GPU: GTX 860M
Ram: 8GB

Make sure you graphic drivers are up to date. Otherwise, yes, there seems to be something malfunctioning, return it under your warranty.