drawPixelLabels took its range from the whole viewport rather than from the
exposed rect it was given, so a 200x40 px hover repaint still walked up to 5000
cells doing mapFromScene + QImage::pixel + drawText for each, only to have the
result clipped away. With hover feedback now rate-limited to 15 Hz that ran ~75
times a second at high zoom, against once per overlay rebuild before the
rendering rework. Intersect with the exposed rect; same in the magnifier.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
leonarski_fandClaude Opus 5
379feac2e9