First load speed

[cben]

[See also ideas on #7. But this deserves it's own tracking issue.]

WebPageTest, e.g. http://www.webpagetest.org/result/150210_D3_EYF/ has a lot of useful things to say.

• [ ] client-side caching is bad to none?!
• [ ] 2/3 of the weight is javascript — unminified, many separate files. Perhaps I should revisit my love for what-I-wrote-is-what-I-serve... Middleware?

Visually, the critical path is time to firepad load. Most important:

• [ ] Check if server-side firepad reconstruction is fast enough (it could be because of cloud<->cloud network), and Ship It already.
  • Understand whether it's even possible to start any client-side JS work before server finishes </html>? If yes:
    • [ ] Experiment using the snapshot as quick preview, via firebase REST api, before I even load other JS.
• [ ] There should be visible indication the document hasn't loaded yet.

[cben]

[also cf. https://github.com/cben/CodeMirror-MathJax/issues/14 for initial math rendering]

[cben]

With Netlify CDN and HTTP 2, I'm gonna assume "good enough" until proven otherwise.