There are a few things that directly affect FPS. The biggest one is Shadows. Turn them off. Turn the effects down to, probably around level 3 on the slider. Turn off V-sync. The biggest thing you can do, depending on your video card. You have the same one I have.
Go to NVIDIA Control Panel. Select 'Configure Surround, PhysX.' Under the PhysX settings, click on the drop down and select your graphics card. If you've not already done so, it will be set to 'Automatic.' Which, in this case, the game will use the CPU. Now, with your GPU selected, the game will be forced to use it instead, taking the load off of the CPU. I normally have 90 to 120 FPS in-game. In some instances it drops down to 50 to 60, a few of the dungeons does that. And in a highly congested area, 35 to 40.
Likewise, after selecting the GPU, go to 'Manage 3D Settings.' Under the Global Settings, select what you want to use. Things like V-Sync set to Use 3D application, or Antialiasing - FXAA, turned off. For selections like Anisotropic filtering all the application (game) control. CUDA - GPU: All, DSR - Factors, 4.00x (native resolution. DSR - Smoothness, 33%, Low Latency Mode, Max Frame Rate, Multi-Frame Sampled AA (MFAA), all off. OpenGL rendering GPU - Auto-select. Power management mode - Optimal Power, Shader Cache On, Texture Filtering 0 Anisotropic Sample optimization, off, Texture filtering - Negative LOD bias, allow, Texture filtering - Quality, Quality, and Texture filtering - Trilinear, On. Triple buffering - Off. Virtual Reality pre-rendered frames, 1.
Then under Program Settings, make sure the B&S Client is listed, if not, add it and make sure you add the 64bit client. What's important is you set everything to "use Global settings" which allows the GPU to control the game and not the CPU. Also, you can turn off seeing the players too while in a dungeon or all the time. That will help if you have too.
You may have to play with the video control settings to find a balance that works for your set up. However, seeing that you're using a 7th gen CPU the ones above I've listed should give you superior FPS. You'll know its working for you at the Character Window if you have your Ge-Force overlay on showing FPS. If you're sitting at 120FPS there, you'll see about the same in-game too, or there about. Just remember, turn off Shadows in-game. Certain games with older engines don't render well and eat up FPS using Shadows.