scene.observe

What every scene load did, and what each loaded scene costs. One read carrying the last load's report — what it produced, the root it replaced and the overlays that went with it, the entity counts on each side, how long each phase took, and every failure it produced with the entity, component or lifecycle hook it is about — plus a per-layer inventory of what the engine attributes to each layer and the per-frame cost of each layer's entrypoint tick. Recorded at each load's own completion point and read lazily, so nothing is measured per frame beyond the tick timings themselves. Answers in edit mode as well as play mode.