[tracking-ish issue] Doc pages are very slow to render

[GuillaumeGomez]

Message from discord:

the https://doc.rust-lang.org/std/iter/trait.Iterator.html page(and only that page?) seems to have a broken search bar that manifests as infinite? loading and high CPU usage in both Chrome and firefox, across stable, beta, nightly, and local versions.

Related:

• Minification makes JS parsing slower
• Open
  search-index.js slows down documentation browsing
• Others?

[ollie27]

The HTML for that page is currently about 12.5MB thanks to #51885. We're now rendering a copy of every trait method for every impl. We could revert #51885 or only render methods that have documentation in the impl.

[JeanMertz]

Just to confirm this issue: I wanted to add that even loading that page is next to impossible on Safari. It takes a very long time, and after it loads, scrolling is so slow that the page is next to useless. I often have to switch to Firefox (my secondary browser) only to read this specific page in the docs.

[crumblingstatue]

Not only is it very slow to render initially, but due to the sheer amount of content on the page, it is also very sluggish to scroll through it on my system.

I also agree that we should show less information by default. A 12.5 MB doc page for a single item sounds ridiculous.

I'd very much prefer if implementors were just listed plainly like so: Implementors: std::ascii::EscapeDefault, EscapeDebug, std::char::EscapeDefault, EscapeUnicode, ToLowercase, ToUppercase, ..., with them being links so you can click on them to go to their doc page.

This amount of duplication is a lot of wasted data. It makes the documentation bloated and slow.

[Stargateur]

Also it would be good to fix this as fast as possible (I have not idea how still a newbie), Iterator are a lot used and be able to read the doc is primordial.

Freeze on Chrome Version 70.0.3538.110 (Build officiel) (64 bits)
Load quite fast on Firefox 63.0.3 (64 bits) ;)

[GuillaumeGomez]

The PR is open and waiting for reviews.

[nocduro]

Has this been deployed? I'm still having really sluggish performance on https://doc.rust-lang.org/std/iter/trait.Iterator.html

Related issue #57281

[steveklabnik]

I don't think it's made its way to stable, check the beta/nightly docs.

[nocduro]

Just tried beta and nightly in incognito and it works about the same. The page doesn't freeze or anything, but scrolling is a bit laggy. Chrome uses ~30-40% cpu when scrolling.

I think this patch is live though, because nightly shows some loading text while the sections are loaded instead of instantly trying to render?

[Stargateur]

yeah, that doesn't freeze but the page still load tons of information, is it possible to have the page that only load what user required, for example, a plus bottom that will only load content when opened ? That would allow to see method, without load everything.

Also, all theses informations are them really needed ? Why did we do this change ?