Math editing performance

[cben]

This is about editing math-heavy text in fully-initialized document; see #19 for init performance.

• cache typeset DOM, reuse if text & token class didn't change
• if changed, use jax methods like .Text(newmath)
  http://docs.mathjax.org/en/latest/typeset.html#manipulating-individual-math-elements
  • use .Rerender() if only token class changed.

Could Hub.Update() do the jib instead a custom caching scheme?!
http://docs.mathjax.org/en/latest/api/hub.html#Update

[cben]

Easy ways to test: painfully slow on Android (specifically, Firefox works well but slow).

[cben]

benweet/stackedit#25 has useful info.

[cben]

Migrated to cben/CodeMirror-MathJax#15 where it belongs.

[cben]

See also cben/CodeMirror-MathJax#14 for first-pass performance which is a much more critical problem.

Closing the bug here.