Rendering for VR currently is more intensive due to the high frame rate and double-rendering (once for each eye).However no one renders a 360 sphere and single-pass stereo rendering is already possible which does the cpu-side rendering for both eyes together. [1] Still, at present, VR rendering is way more intensive than regular rendering and it hasn't yet benefited from decades of optimization work like regular rendering.

The parent post is probably referring to foveated rendering - a research technique which uses eye-tracking to render most of the screen in low quality and areas being looked at in higher quality. (Real vision is perceived something like this - try reading text that isnt in the center of your gaze.) You can do foveated rendering better for a close screen so eventually it's possible that the quality of VR rendering will surpass regular rendering.

[1] docs.unity3d.com/Manual/SinglePassStereoRendering.html

The GPU is faster than a human can move. You don't need to render all around.

Even better, if you render just a couple degrees extra you can double your framerate via interpolation. That way you can have 120Hz head-tracking while only having to render the world at 60Hz.