Follow-up, since I asked the questions above: I spent the evening running Justif against the hardest page I have: three 356px columns of 18th-century text set in IM Fell at ~17.6px with 24.3px leading. I came in curious and left planning the integration.

The numbers were better than I hoped. A full ~5k-word essay justified in about 280ms, and ~36KB gzipped including the en-US patterns. And the output is the part that sold me. The columns look like typesetting rather than CSS, which is the whole thing I'd been grumbling about.

The only snag I hit: a floated initial letter (drop cap) trips it — the first line ignores the float and overflows the gutter. Excluding that paragraph and leaving it on native justify renders perfectly, so it's cosmetic to work around, but a first-class exclusion selector would be lovely. I'll file an issue with the details and our measurements.

Best part: this experiment exposed that our sheets are currently set ragged right, which no printer in 1787 would have tolerated. Your library may be what finally makes us historically honest. Test page for context: federalistreader.org/papers/10/

Thank you for building this!