PXLT-14 · 2.5D performance probe

Worst case on purpose: more actors than a busy town, every one billboarded and animating, on a terrain chunk bigger than the screen. Rendered to a low-resolution buffer and upscaled nearest-neighbour — the actual shipping technique, not a stand-in.
Pass bar: p95 ≥ 60fps on iPhone 15 Pro Max and Galaxy S25 Ultra. Run it with the phone unplugged and not freshly charged — thermal state moves this number more than any code change will.