[ceejayoz]

> Just think about how many engineer-hours Twitter flushed with that silly #! kludge – and then when they switched back, saw an 80% improvement in page load time.

No hours were wasted, and they didn't really switch back. They're just using HTML5's History API on browsers that support it now. Essentially the same mechanism under the hood, just prettier URLs for it.

[acdha]

They did more than just switch to the history API. During that period, if anything went wrong, you saw a blank page and, of course, robots saw only the generic launcher HTML instead of any content.

Now, here's what a tweet looks like without JavaScript enabled:

https://www.dropbox.com/s/me7kinvje7ly781/Screenshot%202015-...

Here's what it looks with JavaScript enabled:

https://www.dropbox.com/s/04pjdlkuht6t2ja/Screenshot%202015-...

(The main difference would be that things like the search & menus are either interactive controls or simple links to basic HTML forms depending whether JavaScript loads)

During the hashbang era you couldn't use a page without a full rendering ending. Now, however, all of the content is available with fairly rich markup:

https://redbot.org/?uri=https%3A%2F%2Ftwitter.com%2Facdha%2F...

[hartator]

I think he was making reference to the DOM rendering in the twitter website which used to be on client side until recently when they have switched back to server side rendering. But, it's very similar to pre-rendering React components on the server then mounting it so it might not be a total waste, that was a fad that didn't make a lot of sense for the time though.