Why would we measure when the page becomes interactive (rather than viewable)? I can't imagine many people interacting with a page within the first second of it being viewable.

The reason lazy-loading wasn't faster on the larger articles is that the loading speed was less reliable. Non-lazy-load times varied by up to 1 second. Lazy-load times varied by over 2 seconds. So even though the fastest load times were from lazy-loading, so were the slowest. For small articles, the load times were very consistent for both load types.

Ryan Kaldari


On Mon, Jul 28, 2014 at 12:02 PM, Jon Robson <jrobson@wikimedia.org> wrote:
Wait... I'm not convinced by this. I'm not convinced you measured the
right things. How exactly did you measure this? Did you include the
HTTP response time?

I struggle to believe that non-lazy loaded pages could ever be faster
and that the improvement was on a half second.

Can you post more details on the tests you ran?
Really you should be looking at numerous things, namely:
1) Time from user request (refresh page) to being able to read the
content (DOM content loaded) - e.g. time the HTTP request takes when
just using the api and just using HTML
2) Time the JavaScript loads and the page becomes interactive (with a
lazy loaded page this will always be 0s and on a non-lazy loaded page
this will always be more as the entire HTML, JS and CSS has to be
loaded)

cc'ing mobile-l


On Mon, Jul 28, 2014 at 11:39 AM, Maryana Pinchuk
<mpinchuk@wikimedia.org> wrote:
> Thanks, Kaldari – I've changed the description in this card[1] to reflect
> your recommendation. Unless anyone objects, we'll remove lazy-loading
> entirely in the next sprint.
>
> 1. https://trello.com/c/fFoRlvxl/3-5-remove-ajax-page-loading-from-alpha
>
>
> On Mon, Jul 28, 2014 at 11:00 AM, Ryan Kaldari <rkaldari@wikimedia.org>
> wrote:
>>
>> I did a spike on the effects of lazy loading pages on save. I tried a
>> variety of different articles and did at least 10 tests in each mode.
>>
>> On stub size articles, lazy loading resulted in a half-second improvement
>> in page loading on average. On larger articles, there was greater variation
>> in lazy-loading time and the averages were virtually identical
>> (non-lazy-loaded time was actually 0.15 seconds faster on average, but this
>> was not statistically significant).
>>
>> So basically, lazy loading results in a small improvement for small
>> articles and no improvement for large articles. Given the extra maintenance
>> required (we have to keep maintaining virtually all of the lazy loading code
>> for this specific use even if we don't use it elsewhere), and the frequent
>> bugs that arise, I would still favor removing this feature.
>>
>> Ryan Kaldari
>
>
>
>
> --
> Maryana Pinchuk
> Product Manager, Wikimedia Foundation
> wikimediafoundation.org