I recently blogged a 'tear down' of an award winning mobile career website. It was an eye opener at how poorly the site was constructed and how much candidate potential was being lost from the site being slow. Here is are my top 4 learnings when it comes to mobile optimisation.

Avoid Custom Fonts

Typically it is sensible to avoid custom font downloads. The font is typically large and adds times to the site download speed. The font is also present on every page, increasing the memory footprint of the site in the mobile browser. Where you do use custom fonts choose fonts that are small in file size.

Avoid Resizing Images on the Device

Many, none adaptive, mobile sites load the images designed for desktop on the mobile device and through CSS instruct the browser to resize the image. This involves an expensive download increasing the download time. It also uses more memory on the device and requires more processing time on the device.

Avoid Including the big Javascript Library

Javascript libraries have become common place in web development and have improved quality and functionality of the web. Unfortunately few developers remember to optimise the libraries they include, typically the entire library is included even if only a sub element is used. Most common javascirpt libraries have tools to extract just the elements needed. This increases the file download size and time, it also increases the processing time for the browser which on desktop is negligible but on mobile can be visible.  Consider alternative libraries, for example at my company our platform Pocket Recruit uses Zepto.js for mobile uses (apart from winPhone) and Jquery for desktop.

Minify and Compress JS and CSS

Minification is an automated process which should be part of the release steps. It reduces file size of code at the cost of readability of the code, which is acceptable for release (not in development). Additionally to minify, sites should compress the code to increase download speed. Ideally the JS and CSS should be merged into two single files, this reduces the overhead involved in DNS lookup and requesting a file.

AuthorDave Martin