The headless bake worker renders on SwiftShader (CPU), where per-frame
vertex/draw cost dominates the whole capture — but a bake only reads the
built scene graph; the pixels are thrown away. `?disable=draw` (same
diagnostic-param family as postFx) renders an EMPTY scene each frame
instead of the real one: useFrame systems and scene-ready keep ticking,
per-frame cost collapses to a 64x64 clear.
Rendering nothing at all does NOT work: with zero submitted frames
Chromium's no-damage scheduler throttles rAF to exactly 1Hz (measured),
starving the very systems the bake needs — hence the empty-scene draw.
Measured on the office scene (200+ items) with a real GPU: capture
45.0s -> 8.4s (settle 37.6s -> 4.5s); output equivalent to a normal
render (structural GLB diff clean; the ±13-accessor variance exists
between normal runs too). CPU-only (worker) numbers via the prod-image
container against a preview deploy.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
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