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Increased Fully Loaded Times in IE-10/11? - Printable Version

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Increased Fully Loaded Times in IE-10/11? - DigitalJeff - 03-01-2014 12:34 AM

We've been running daily tests all week to capture pre/post timings for some changes we implemented on 2/26 in the evening. We moved some calls from client-side to server-side and eliminated 9 HTTP requests.

24-pre: http://www.webpagetest.org/result/140224_70_KRW/4/details/
25-pre: http://www.webpagetest.org/result/140225_KD_RCV/5/details/
26-pre: http://www.webpagetest.org/result/140226_V9_GJF/3/details/
27-post: http://www.webpagetest.org/result/140227_33_H09/9/details/
28-post: http://www.webpagetest.org/result/140228_2Z_GDE/5/details/

Fully Loaded Time improvements were smaller than anticipated and now the end of the waterfalls (from 2/27 forward) don't align with the Fully Loaded Times. The links above are all from IE-10 tests, but the behavior is the same for IE-11 and Chrome. Some of these timing differences are approaching 2 secs.

Is there something that's now processing after the last request completes in the waterfall and it's just not being shown? If so, how can we shed some light on it to improve?


RE: Increased Fully Loaded Times in IE-10/11? - Bas-tester - 03-01-2014 01:48 AM

The difference I think you are running into is the difference of the document complete (aligns with waterfall) and the fully loaded time.

This is some copy/pasting from what I have found on it with a bit of my own interpertation:
The Document complete time is measured to when the browser fires the onLoad event.

There could be an ellement that needs more time, for instance a flash object which could do things in the background that can't be seen by the webpage test.

Or that javascripts do things in the background, for example wait for x number of seconds before they fire.

I see a call to which loads several seconds after the page load, it's called from the AA.js script but that is at this moment on the website, not in the webpagetest result.

RE: Increased Fully Loaded Times in IE-10/11? - DigitalJeff - 03-01-2014 02:44 AM

That's interesting because the fp_AA.js script has been making a call to the NonExistentImage gif for a couple months now, only that script used to be called further up the waterfall prior to the changes this week. I presume this week's changes must have pushed the fp_AA.js script call towards the end of the waterfall and now our Fully Loaded Times are being impacted by that call in the background.

Could this particular background processing negatively impact our Visually Complete timings as well? I noticed they're up the last couple of days too (see pre/post URLs above).

RE: Increased Fully Loaded Times in IE-10/11? - pmeenan - 03-05-2014 03:19 AM

I'll take a look, that looks like a bug - the fully loaded time should match the end of the waterfall. Looks like some activity is being tracked that isn't included in the final results and it shouldn't be.

RE: Increased Fully Loaded Times in IE-10/11? - DigitalJeff - 03-06-2014 12:46 AM

For IE or other browsers, will background tasks show up in the waterfalls?

The other thing is that Chrome timings have way more variability and are quite a bit higher that IE or FF. Any thoughts?

26-pre: http://www.webpagetest.org/result/140226_03_GJS/
27-post: http://www.webpagetest.org/result/140227_55_MTV/
05-post: http://www.webpagetest.org/result/140305_WD_D9J/

RE: Increased Fully Loaded Times in IE-10/11? - pmeenan - 03-07-2014 07:57 AM

There shouldn't be any background tasks - we run Chrome with flags to disable all of it's background activity (but no, they wouldn't show up on a SSL site unless you did a tcpdump).

RE: Increased Fully Loaded Times in IE-10/11? - DigitalJeff - 03-08-2014 01:49 AM

Some additional information and patterns RE: increased FLT's for several browsers.

For IE-8, IE-9, two calls to NonExistentImage gif get executed and are shown in the waterfall, yet Fully Loaded Times don't align to waterfall.

IE-8: http://www.webpagetest.org/result/140306_9Y_MS5/3/details/
IE-9: http://www.webpagetest.org/result/140306_NY_MS2/8/details/

For IE-10, IE-11 and Chrome these same calls are made but not shown in the waterfall, yet the Fully Loaded Times appear to include those calls (FLT doesn't align to the waterfall), even though the calls are not customer impacting. Some of the Fully Loaded Time delays are rather large.

IE-10: http://www.webpagetest.org/result/140306_G7_MSZ/1/details/
IE-11: http://www.webpagetest.org/result/140306_X4_MSS/9/details/
Chrome: http://www.webpagetest.org/result/140306_SX_MSA/4/details/
FireFox: http://www.webpagetest.org/result/140306_G1_P3J/6/details/

Any idea as to why these 2 non-customer impacting gif requests appear to be treated differently between browsers (e.g. shown vs. not shown in waterfalls) by WPT and why the Fully Loaded and Visually Complete times vary from the waterfalls by so much? We do benchmarks using FLT's and there's alot of variability between the waterfalls and FLT measures with the various browsers in WPT.

RE: Increased Fully Loaded Times in IE-10/11? - DigitalJeff - 03-11-2014 10:13 PM

We're still seeing Fully Loaded Times that don't align anywhere close to the end of our waterfalls. See links and gaps between FLT's and end of waterfalls.

IE-8: http://www.webpagetest.org/result/140311_YC_ET5/9/details/ 5.7s (+1.0s)
IE-9: http://www.webpagetest.org/result/140311_4G_ETC/9/details/ 5.1s (+1.0s)
IE-10: http://www.webpagetest.org/result/140311_K3_ETF/6/details/ 5.8s (+1.0s)
IE-11: http://www.webpagetest.org/result/140311_DT_ETJ/3/details/ 6.2s (+1.8s)
Chrome: http://www.webpagetest.org/result/140311_X0_ETM/7/details/ 5.6s (+0.9s)
Firefox: http://www.webpagetest.org/result/140311_G6_ETN/4/details/ 7.6s (+3.5s)
Safari: http://www.webpagetest.org/result/140311_JZ_ETV/8/details/ 5.3s (+0.7s)

These unexplainably high FLT's are occurring even after implementing a CDN last evening. The site is definitely much snappier after implementing the CDN. So, if we can't determine why this is happening and begin to reconcile FLT's with the waterfalls I think we'll be forced to abandon the WPT metrics and find another tool that provides more accurate load timings.

Comparable measures with other dev tools:
- With YSlow plug-in on FF, we're seeing load times in the 4.2sec range
- With Dev Tools on Chrome, we're seeing load times in the 4.4sec range

Any assistance in trying to figure this out is appreciated.

RE: Increased Fully Loaded Times in IE-10/11? - pmeenan - 03-12-2014 01:31 AM

IE 10, IE 11, Chrome, Firefox and Safari are all fixed now. Working on the other test agent code that is used for IE < 10 right now.

RE: Increased Fully Loaded Times in IE-10/11? - pmeenan - 03-12-2014 02:25 AM

ok, the IE < 10 agents should also be fixed now: http://www.webpagetest.org/result/140311_YD_RBK/

The end times right now look like they are beyond the waterfall but that's because of the 2 failed requests for NonExistantImagexxx.gif at the end of the page (one of them referencing localhost).