A single ResizeObserver refits the frames, reading each rotor before any wrapper is
written: a per-view one arrives in a callback of its own, so the browser laid the
document out again between two frames. pm-pagecount is announced only where the layout
differs from the last announcement — every reader re-reads the whole document from it and
writes back, which is another pass. Both node views also leave the DOM alone when update()
brings the same attrs object. A 460-page file holding 450 frames and two indexes settles
2.4 s earlier and is named 200 ms earlier, with every spacer and page number where it was.
Steffen Becker
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