anakaa4, you may reduce resolution in Oculus: in the graphics settings menu move the "Oculus render scale" slider. BTW this is an official method, purposed in the Oculus Best Practice pdf. So low framerate in Oculus is not an only SE problem these days.
To prevent fps drop while generating stuff, change the timing settings in the main.cfg:
LoaderMaxTilesPF 2 // max landscape textures created per frame
LoaderMaxTimePF 20.0 // max loading/creating time per frame (milliseconds)
CleanMaxTimePF 20.0 // max memory cleaning time per frame (milliseconds)
LoaderMaxTilesPF can be reduced to 1, the rest can be reduced to less than 1/75 = 13 ms, but I guess this will not help because you have too weak graphics card for comfort playing in Oculus.