Re: [selectors] Finding a way to run "complete" profile selectors in CSS

On 07/11/2013 04:28 PM, Tab Atkins Jr. wrote:
> Basic issue: we've got cool new selectors in Selectors 4 (and more
> that we'd like to add in future levels) that we aren't allowed to use
> in normal CSS because they're too slow.  Being able to use them in JS
> is great, but it's really annoying that we can't do so in normal CSS.
>
> The question then is how we can mitigate the problem that is currently
> preventing us from using them in normal CSS.  The issue is that the
> new selectors are too slow to reasonably run as often as we run other
> selectors, so an obvious solution is to allow their use in some way
> that indicates they're not run as quickly as other selectors.
>
> ... Add a new at-rule, perhaps named @defer ...
>
> What are the use-cases for "slow selectors", how well are they
> addressed by either of these two solutions, and is there anything
> better we could do?

This is silly. I'd rather just wait until these become critical enough
that someone wants to implement them with appropriate optimizations. [1]
Speccing, implementing, teaching, and asking authors everywhere to use
some kind of crazy-awkward performance hack is not imho good for the Web,
or a good use of anyone's time.

~fantasai