You may be onto something here, @ColinRobnsn, but not for the reason you may be thinking. I did some digging in the Oculus SDK, and found this:
The FOV-Tangent Multiplier setting is provided by the Oculus Debug Tool, as shown in the following screenshot. This setting can be used to improve the viewing experience when streaming game play to an audience. With this feature, you can increase the size of the field of view (FOV) as it appears on mirrored flat screens, relative to what is displayed within the headset. This makes it more comfortable to view streamed or recorded game play since the FOV that is used within the headset can appear too constricted on flat screens, and thereby cause motion sickness on the part of the viewing audience. The FOV-Tangent Multiplier feature has two settings: Horizontal and Vertical. Simply set these values to the desired multiplier for the FOV.
Source URL: Oculus Debug Tool | Oculus Developers
So, as I read this, this setting does not affect the Oculus display resolution at all, but only what’s being displayed on your monitor. It makes sense (at least to me), that reducing (or even radically reducing) this setting would decrease the load on both the GPU and the CPU of the computer, thereby translating into more FPS in the Oculus display. I’m going to test this theory this evening. Thanks for the lead!