[ubuntu] Performance seems way worse than it should be when involving the GPU

I have a Lenovo T540P with an nvidia graphics card - the 730m. On Windows, gaming is smooth, most GPU-related things are. However, on Ubuntu, I've noticed really terrible performance in two areas:

1) HD videos in VLC, using the nvidia drivers
2) Wine gaming. I've been playing Path of Exile, which I've run on much weaker systems at much higher resolution. On WINE, I'm ruing it using only 720p and all of the graphics options down low. Still I run into huge lag issues when there are a lot of GPU heavy actions going on.

I realize the 730m is not exactly the most powerful card, but, as I said, I've had a weaker GPU before and had better performance.

So, basically, I'm looking to improve GPU performance specifically.