Poor Performance Under Linux

I feel like I should be getting better performance than I am. I am usually between 40-50 FPS but get drops down to 30-35 sometimes. I am trying to figure out if it's a driver issue, an issue with the Linux version of POE or something else. My CPU usage rarely gets as high as 80% on a few cores and when it does my FPS is fine. My entire RAM usage doesn't go above 2.5GB. I am using the latest driver for my GPU. I got better performance from Crysis 3, The Witcher 2 and Far Cry 3 which in my opinion should be the more demanding games albeit I played those on Windows.

My system has the following:

AMD FX-8350 @ 4.5 Ghz | 12GB DDR3-1600 CL10 | Club 3D Radeon R9 280X 3GB | OCZ 128GB Vertex 4 SSD | Linux Mint 17.2 64 bit

I have played the first little bit of POE on my Windows 7 partition and the lowest it got was 72 FPS which it was only at for a few seconds. The rest of the time it ran between 85-118 FPS. I will also note that there was support for 144 Hz on Windows while Linux lacked that. I'm not sure yet if this huge FPS gap had anything to do with Linux being at 60 Hz or Linux just not getting as much love from Obsidian. I don't think Unity is to blame though.