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Responsive Web Design with HTML5 and CSS3 Essentials by Asoj Talesra, Gaurav Gupta, Alex Libby

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Understanding why pages load slowly

Although we may build a great site that works well across multiple devices, it's still no good if it is slow! Every website will of course operate differently, but there are a number of factors to allow for, which can affect page (and site) speed:

  • Downloading data unnecessarily: On a responsive site, we may hide elements that are not displayed on smaller devices; the use of display: none in code means that we still download content, even though we're not showing it on screen, resulting in slower sites and higher bandwidth usage.
  • Downloading images before shrinking them: If we have not optimized our site with properly sized images, then we may end up downloading images that are larger than necessary on a mobile ...

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