[mortenjorck]

That's just it, though. It's the exact same number of pixels. It's a single 1080p screen divided in two.

[moistgorilla]

you are rendering from two different angles. its not the same as taking one rendered frame and cutting it in half

[mehwoot]

Number of pixels isn't the primary cost of rendering, unless you are using ray tracing.

[higherpurpose]

You lose some performance with V-sync, which is necessary.