I would bet that if you profile Firefox WebRender there very little of the time is actually spent rasterizing glyphs. It takes like 10 microseconds to rasterize

I would bet that if you profile Firefox WebRender there very little of the time is actually spent rasterizing glyphs. It takes like 10 microseconds to rasterize a small glyph, it's really nothing. Source: This is what I spent a ton of time profiling in the past. And Safari should just rerasterize glyphs while zooming. In 2022 there's no technical reason why it can't.