Load comments using:

• XHR html + innerHTML - what GitHub uses when navigating.
• Server render
  - what GitHub uses before JS.
• XHR json + innerHTML - kinda like what GitHub is doing now, but sends JSON rather than HTML.
• XHR ndjson + innerHTML - processing the incomming data in chunks.
• Streaming iframe hack - crazy enough to work?
• Streaming element - the iframe hack as a web component.
• Streaming parser - using parse5 with DOM adapter.
• Streaming service worker
  - Server render powered by service worker