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Monitor client performance & solve responsive images

  • Jul 10, 2013 · 6:30 PM
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I'm excited to announce the second instalment of Vancouver Web Performance! The event will be hosted at Mobify, #300 - 311 W Pender St on Weds July 10th @ 6:30PM.

We have two fantastic speakers - read on for details!

Speaker #1: Kalvir Sandhu,, founder, serial entrepreneur & guru of performance measurement

Monitoring client side performance to make your users happy

You've finally taken the plunge and built your next hot application in one of the many JS frameworks or libraries out there. You've tested it locally, profiled & tuned it, but how are your customers using that app and what is their experience? How can you see if it sucks in their browser or mobile? Is it making them sad? My talk will help you reveal this information and help you make your users happy.

My talk will explain the new challenges introduced when building a JS app and why measuring performance is still important. It will cover who is using what to monitor and improve applications. I will discuss the techniques in which they work and how developers could build out their own custom metrics using events fired in JS or APIs available in the browser.

Speaker #2: Shawn Jansepar, Mobify, dev lead, hacker, hockey & schwarma lover

Instant & automatic responsive images

The current crop of responsive image solutions are a pain. Developers desperately need a solution that automatically generates smaller images for smaller devices from a single high resolution image - and ideally this automatic solution would only make one request per image and would be 100% semantic and backwards compatible. I will be talking about how you can use Mobify.js to satisfy these requirements using Mobify's free back-end service or a back-end of your choosing, and how browser vendors can improve support for responsive images in the future.

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  • Jaime B.


    Two awesome talks by Kalvir and Shawn! Thanks Mobify for hosting!

    I wanted to add a bit of info on a few performance related approaches by Microsoft Research:

    1) Silo - chunk-based delta-encoding for DOM storage -

    2) Mugshot (deterministic capture/replay for client-side) -


    2 · July 12, 2013

    • Peter M.

      Both really interesting pieces of research. It's too bad we aren't seeing more use of delta-encoding. CloudFlare does provide Railgun, but that's just origin<->edge.

      1 · July 18, 2013

  • Daniel B.

    I found this article [1] and the accompanying discussion on HackerNews [2] to be really interesting. Article [1] talks about sharpening downsized images to get more visually pleasing results. I think someone also mentioned that trick after Shawn's talk yesterday.

    The HN discussion mentions another approach: Using larger-than-target-size JPEGs *compressed at zero quality* and having them scaled down by the browser. I ended up using this method for a private blog / image gallery thing and it works well.

    2 · July 11, 2013

  • Jorge P.

    Here's the talk that I mentioned from Yehuda Katz about web standards. Around minute 21 he describes what we should be able to do with web components. He uses a custom-image element as an example.

    It's a really great video overall if you care at all about the future of the browser and web standards.

    Thanks Kalv and Shawn for your presentation, learned lots.

    July 11, 2013

    • Peter M.

      Thanks Jorge! Really interesting to see this. I definitely see that I'm not alone in feeling that devs need to move ahead of browsers. :)

      July 18, 2013

  • Daniel B.

    [ posting this as two messages because of the max length limit :) ]

    It's especially nice that almost no work is required on the client's side. You just use plain <img> tags and specify a target size. The downside is that scaling down the images is costly on mobile devices. The downscaling incurs a noticeable delay and probably increases peak memory usage. On the long run it'll probably be bad for battery performance because of the high CPU load.

    Depending on your use case this might still be a good idea to try.


    1 · July 11, 2013

  • Peter M.

    Thanks for coming out everyone! There were some great questions. Look forward to seeing you again around mid-Sept. As always, if you would like to give a talk or there are topics you'd like to see discussed, please get in touch with me.

    1 · July 11, 2013

  • saem

    Great venue, and good speakers.

    2 · July 10, 2013

  • Stephanie H.

    The Apple Developer library doc that mentions the file size limitations I ran up against is here: Do a page search for "Know iOS Resource Limits". Blackberry was also subsampling our ginormous image but I couldn't find a published explanation for its behaviour.

    Great event, thank you to both speakers :)

    July 10, 2013

  • Jean-Francois A.

    Great talks and great event overall. Well done!

    July 10, 2013

  • Scott

    Both topics interesting; client-side performance monitoring is new to me so the cross section of tools and approaches was helpful. Mobify's approach to responsive images was cool.

    And... beer and pizza? What could possibly be wrong with that?

    July 10, 2013

  • Daniel B.

    Really interested in the talk about responsive images. Though right now I'm still kinda stuck in traffic :)

    1 · July 10, 2013

  • Chet W.

    On vacation at the time.

    July 3, 2013

  • Alfred K.

    Should be interesting :)

    June 24, 2013

  • A former member
    A former member

    Those are very interesting topics, too bad I cant make it.

    June 24, 2013

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