RE: {minutes} 2014-04-26 Web Performance Working Group: Resource Priorities, HRT2, Beacon, etc.

David, thanks for clarification and updates. As I wasn't at the F2F, and am still the new guy, so I'm just working through the backlog which stated this should be removed.

That said, I'm trying to understand the use cases and how postpone would work. In many instances, you need to have the metadata information to determine layout/bounding box. Without determining layout in those instances, how would you know when it has been scrolled into view? You would need a good bit of information about layout and have zero dependencies on getting that layout information from the resource before you could get the gains. Otherwise, without a specified layout you would actually have terrible negative performance implications as well. 

While I can see the desire to have this feature provided by the platform in theory, the implementation seems to have a lot of traps. 

Tobin


-----Original Message-----
From: David Newton [mailto:david@davidnewton.ca] 
Sent: Sunday, March 30, 2014 5:10 PM
To: Tobin Titus
Cc: Philippe Le Hegaret; public-web-perf
Subject: Re: {minutes} 2014-04-26 Web Performance Working Group: Resource Priorities, HRT2, Beacon, etc.


On Mar 30, 2014, at 7:21 PM, Tobin Titus <tobint@microsoft.com> wrote:

> Thanks, David.
>  
> From the TPAC notes:
> http://lists.w3.org/Archives/Public/public-web-perf/2013Nov/0091.html
>  
>  
> Under Meeting Summary, agenda item "3. Resource Priorities":
> "Additionally, there were concerns with postpone. The WG agreed to scope the spec back to lazyload and work from there."

Thank you, Tobin. I did see that in the summary, but looking at the actual Meeting Minutes, it appears that this was concern with the postpone CSS property, not the attribute:

> Alois: If you have a postpone on the background image, we don't know that the element is visible yet until we do styling.
> 
> Jason: IE doesn't even download the resources from CSS until the formatting is done.
> 
> Jason: I think we should remove the postpone CSS property as the browser will already do this work.
> 
> Anne: In many cases, it's hard to know when the image will be in the page.
> 
> Jason: Seems like there is agreement that there is a need for lazyload / postpone, but there may be some confusion in the spec.
> 
> Anne: I think I agree with that.
> 
> Jatinder: Looks like we need to remove the CSS property.
> 
> <Alois> preload none on video 
> http://www.w3schools.com/tags/att_video_preload.asp
> 
> Jason: I think we should scope this to lazyload and then consider adding postpone later on in an Level 2 based on feedback.
> 
> Anne: I think we should consider starting with lazyload. For example, the user agent could interpret lazyload to mean postpone based on data.

>From what I can tell, there was no such concern with the attribute, and the decision was only about scoping back the CSS property.

Thanks,
Dave

Received on Tuesday, 15 April 2014 23:07:59 UTC