resolutionScale property
The resolution the reflections are traced at, as a fraction (0..1) of
the render size. 1.0 traces at full resolution; lower values trace
(and blur) the reflection layer more cheaply and bilinear-upscale it,
leaving the rest of the image full resolution. The single biggest
performance lever, and the main one to lower on mobile.
Implementation
double resolutionScale = 1.0;