- July 5, 2016, 4:36 p.m.
Assuming you're running in Fullscreen or Windowed mode, resolution should change the game world's resolution; however, for retina display macs, it has half the effect by default. Retina display macs default to a render scale of 50% in legion, which means for what ever resolution is selected, the game world will be rendered at half that resolution. For example, a 5k iMac with a resolution of 5120x2880 will default to a 5120x2880 resolution with full scale, crisp, UI and will render the game to a 2560x1440 backbuffer. The main motivation for this is because every mac with a built in retina display currently ships with a mobile GPU that has trouble rendering the game at full resolution.
If you want to increase the game resolution without changing the UI, you can change the render scale slider in the Advanced tab to anything you want (65%, 75%, 100% etc). 100% is the WoD default and default for non-retina macs.
SSAA (supersampled antialiasing) sets the render scale to 200% to do its supersampling, so in the iMac's case, SSAA would render the world to a 10240x5760 backbuffer, apply the AA and then supersample the backbuffer to the screen, which unsurprisingly would bring that mobile GPU to a screeching halt FPS wise.
It's also worth noting the AA options dropdown on the first graphics settings page will set your render scale to the default value, 50%(retina mac), 200% (ssaa) or 100% (everything else). If you want to change your AA mode/settings without changing the render scale, you need to change your AA mode/settings from the advanced tab. The AA dropdown on the first page is a set of presets. If you don't want to use the limited set of presets, you need to change the AA/render scale options from the advanced tab exclusively.