New laptop has better gpu than desktop but performs horribly?

I just bought the lenovo y40-80 the 1400 dollar one and it has 4 gb of vram, it has an r9 275x. It also has a dual core Intel core i7 5500U.
My desktop has an amd a10 5800k overclocked to 4.9 ghz (quad core) and my gpu in my desktop is an r7 260 by power color and has 2gb of vram. Why do I get half the fps I get on my desktop on my laptop?

Because your desktop GPU is better, mobile GPUs go by a different labeling system than desktops do, the R9 275X is only as strong as a R7 250x