I've been dreaming of rendering the Ghostscript tiger for a long time, now I'm dangerously close to quality rendering. Sometimes using a library lets you focus on what you care about, heh. I used nanosvg.h (instead of my own shitty less complete SVG parser) to parse the SVG file into a list of shapes, each shape composed of a set of cubic bezier outline paths. These paths are naturally cached for efficiency reasons. I ripped a piece of code out of nanosvgrast.h to convert the bezier outlines to line segment outlines using a recursive subdivision algorithm. The segments outlines are cached as well, but the conversion is redone whenever the scaling level (zoom) has changed by more than 2x.
Everything else is computed end-to-end as before, making tiles with localized geometry on the CPU, then rendering each tile using the equivalent of scanline rasterization on the GPU. Still scales reasonably well, and I'm hopeful to find out what options this approach affords. While there are some drawbacks compared to tesselation, it's a less data-intensive approach, and probably more flexible all considered.