iris APK only; the Compose one is unchanged. Iris reported stuttering
when flinging that is much harder to notice with a finger on the scroll.
Two of the four findings are the report rather than the renderer: the
blocking swapchain acquire was counted as iris's CPU time, and nothing
could say a frame was never produced (`late` is cost, not cadence). The
report now splits every phase into build/acquire/submit and carries a
`missed vsyncs` count.
The two real ones are the frame loop: it asked for its next frame at the
end of the callback, so a frame past the vsync boundary cost a second
one, and the fling was advanced on the wall clock rather than the vsync
the callback carries -- which is the asymmetry with a finger drag, whose
positions come from the finger's own timestamps.
Also opt-level "s" -> 3 for the Android build: p90 0.15ms -> 0.09ms of
iris's own per-frame work, for 1.8 MB of APK.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>