> I think you can tessellation on the CPU in an adaptive fashion (e.g. based on curvature or similar) and update that on a per frame (add, remove tessellation points) basis rather than re-tesselating from scratch each frame.
The GPU’s hardware-implemented tessellation is (a) not compatible enough. It’s OK on Windows because Microsoft requires them for GPU vendors to declare the support of Direct3D 11. On the rest of the platforms, support across GPU vendors varies. And (b) doesn’t help much for 2D vector graphics. The hardware tessellation can be good for terrain, trees, or other triangle meshes in 3D space. Doesn’t help much for these Bezier curves/elliptical arcs for 2D shapes. Especially so for stroked paths.
Counter-intuitively, stroked paths are harder to render than filled ones. The offset of Bezier spline is not representable as another Bezier spline. Also, strokes have more parameters on input: line caps, join types, dashes, miter limit, etc.
> The main limitation in JS is the lack of really great multithreading
Also lack of SIMD. Also, the code in general is slow compared to C++, C# and many other statically typed languages. It’s incredibly hard to generate fast code from very dynamic languages like JS or Python, where everything is a hash map.
> I do not think you need it here.
Here’s my code which offloads CPU-bound pieces of 2D rendering to other CPU cores: https://github.com/Const-me/Vrmac/tree/master/Vrmac/Draw/Tes... Multithreading helped a lot.