I use webpagetest.org to test my website very often.

When I used a couple of remote desktop computers on their site, my TTFB (time to first byte) measures between 1 and 400ms. However, on nearly all mobile tests, from devices from the RealMobile Networks (headspin.io) category, my TTFB measures in at least 1500ms (except for San Francisco which measures at 100ms). My server is located in Quebec and the same one was used with the exact same configuration with no heavy load on the server and I ran each test at least twice.

I understand that there are some variances in the TTFB, but I don't understand if its really true that the TTFB for mobile devices can be significantly that high for a long distance.

I feel like my low income on my mobile site might be due to the high TTFB for mobile devices.

Could it be that I'm using an unreliable tool to test mobile TTFB?

Any suggestions on what I can do to get an accurate TTFB reading from a mobile device to my site so I know where I actually stand?


1 Answer 1


Usually it's good practice to test your website on as much sources as you can find as long as they remain formal and not spam sites.

I think that https://www.google.com/webmasters/tools/mobile-friendly/ gives the most accurate results, if you are talking about interface testing, then use the built in responsive tools for the browsers.

Also the results I get in webpagetest.org shows "First load 1,5 sec" and "Repeat load 3,5 sec" which is hillarious

  • It is hilarious looking at the numbers at first, but I'm trying to figure out the whole reasoning and if theres even anything I can do at my end to solve this issue? or maybe its just the headspin.io networks that are bad? I don't know. Mar 15, 2016 at 2:37
  • In my opinion webpagetest.org isn't a good source, it is impossible to load the page faster the first time and slower on the following, also it doesn't give any recommendations or valuable information, google-mobile-friendly gives you recommendations on how to improve your mobile performance, also as I said it is good to use multiple validators for testing.
    – knif3r
    Mar 15, 2016 at 7:38
  • @Mike it's actually totally possible to load a page faster the first time than on subsequent loads. Depends on how you're defining "load the page." You might be interested in these: webpagetest.org/forums/showthread.php?tid=12656 and webpagetest.org/forums/showthread.php?tid=11933
    – bennlich
    Apr 18, 2016 at 17:25

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