Render the tabs only once

[Mihonarium]

🚀 Feature

To render all the TabItems instead of rendering just the default one, so click on a tab label just changes what tab is visible instead of triggering the rendering of the tab in the runtime of users' browsers.

Have you read the Contributing Guidelines on issues?

Yes.

Motivation

With a large code block under a tab, there's a lag between clicking on a tab and the tab being shown.

Pitch

If all the tabs are being rendered and clicking on a label just changes what tab is visible instead of rendering a new tab, it would:

• allow search engines to access the content of the tab (currently, only the content of the default tab is rendered in HTML),
• get rid of noticeable and annoying time between the tab being clicked and being shown when the tab rendering takes some time (e.g. if there's a large code block).

[slorber]

A problem is: rendering all tabs ahead of time can also introduce a lag when we navigate to a large page with a lot of tabs in it :)

Maybe we could have an option to make them render more lazily, but not sure this would play well with server-side rendering, SEO and hydratation...

[lex111]

Implemented in #3706.

[Mihonarium]

Implemented in #3706.

Good job, thanks!