WebPagetest Forums
Can someone help me read this waterfall chart? - Printable Version

+- WebPagetest Forums (https://www.webpagetest.org/forums)
+-- Forum: Web Performance (/forumdisplay.php?fid=3)
+--- Forum: Discuss Test Results (/forumdisplay.php?fid=4)
+--- Thread: Can someone help me read this waterfall chart? (/showthread.php?tid=13146)



Can someone help me read this waterfall chart? - catalyst07 - 08-08-2014 07:20 PM

I would love to know what I can do better to improve this sites performance.

I used webpagetest to see if anything was blocking but I ended up having this weird chart instead...

Let me know what you guys with more experienced eyes see when you look at these - I attached the first visit waterfall and the second visit:


RE: Can someone help me read this waterfall chart? - pmeenan - 08-08-2014 11:48 PM

FWIW, the URL for your test result is permanent and shareable. Here is a good blog post and video on how to read network waterfalls: http://www.webperformancetoday.com/2010/07/09/waterfalls-101/


RE: Can someone help me read this waterfall chart? - catalyst07 - 08-09-2014 03:38 AM

Thanks pmeenan - I should mention that I have some experience reading waterfalls but wanted a second opinion/set of eyes on it - mainly the huge gaps are what's puzzling me, and if there's anything else major you guys notice.

Also - are SSL handshakes normally that long? What's the general consensus here on keep-alives and SSL?


RE: Can someone help me read this waterfall chart? - pmeenan - 08-09-2014 03:56 AM

SSL handshakes can be several round trips but with proper tuning you can get it down to 1 RTT (at least with Chrome). Ilya Grigorik gave a great talk at Velocity a few months about it with all you need to know to make it fast: https://www.youtube.com/watch?v=0EB7zh_7UE4&list=UU2YCnM2rCPlRkVT91fNvVkQ

Gaps tend to be browser CPU activity (parsing, building DOM, executing script, etc) and are going to depend on the test system that the test was run on. Using the "Dulles Thinkpad" location runs on fast Core i5's if you want to see what it looks like on fast hardware.

If you want the nitty gritty of what is going on, with Chrome you can turn on timeline and trace capture. The timeline will give you some high-level information about javascript, layout and things under the control of the page. The trace will tell you at a very low level exactly what the browser is doing (the Chrome dev team uses the traces for their own development, it's not necessarily targeted for site developers).