Some extra info here:
i7-2600k / AMD R9 290 / 16GB RAM
Windows 7 64-bit / SunTemple Demo / vsync on
Oculus 0.4.2 + UE 4.5.1 VANILLA
hmd mirror off / sp 135 → 75 fps (75 to 90 with vsync off)
hmd mirror on / sp 135 → 50 to 60 fps on almost whole level
hmd mirror on / sp 125 → 55 to 70 fps on almost whole level
hmd mirror off / sp 135 → 75 fps (75 to 85 with vsync off)
hmd mirror on / sp 135 → 55 to 65 fps on almost whole level
hmd mirror on / sp 125 → 60 to 75 fps on almost whole level
sp 135 → 70 fps on last corridor statues, first big statue, ceiling
sp 125 → 75 fps
Oculus 0.4.3 + UE 4.5.1 VANILLA
(same performance with OCULUS GITHUB version)
hmd mirror off / sp 135 → 0 fps
hmd mirror on / sp 135 → 37.5 fps on almost whole level
hmd mirror on / sp 125 → 37.5 fps on last corridor statues, first big statue, ceiling
hmd mirror off / sp 135 → 37.5 fps on almost whole level (70 to 80 with vsync off)
hmd mirror on / sp 135 → 37.5 fps on almost whole level (70 to 80 with vsync off)
hmd mirror on / sp 125 → 37.5 fps on last corridor statues, first big statue, ceiling
sp 135 → 70 fps on last corridor statues, first big statue, ceiling
sp 125 → 75 fps
NOTE:
When i say “on almost whole level”, i mean that fps can be a bit higher if looking straight to a simple wall or looking at the floor for instance.