Your video graphics card should have atleast 1GB of VRAM for better performance in Lightroom 6/CC.
Here is the article that you can refer for the list of supported/tested cards or for troubleshooting :
I don't see my graphic card listed there (Nvidia GeForce GT 750M with Optimus Technology) but it has 2G of VRAM so I think it should work better. In photoshop it works much better
The performance difference may not originate with the video card. First, try disabling GPU support within Lightroom to see if this makes a difference. If things speed up, we know it is a video card issue. If no change, we are likely dealing with something else slowing things down.
Overall, see this documentation for information about Lightroom performance: