In his Faster Mobile Sites, More Revenue
presentation at Google Conversions 2017 in Dublin, Ireland, Guillaume Derolez shared a number of ways to optimize the loading time of mobile Web pages. Here’s my notes from his talk:
- Smartphones are performance constrained but users have high expectations of performance.
- Mobile commerce is an upper funnel affair: customers have a 50% chance to engage with your brand on mobile first.
- Most conversions touch 2.6 devices.
- The average load time on mobile commerce sites is 7 seconds for US retail mSites.
- As page load time goes from: 1s to 3s the probability of bounce increases 32%
- Mobile pages that load 1s faster see up to 27% increase in conversions.
- So how fast should mobile pages be? The target for page loading is one second but on a 3G connection, 600ms is needed for overhead which really leaves you with 400ms for round-trip server connection.
- Top three areas to investigate in order to make mobile Web pages faster: images, non-minified resources, number of requests.
- Images: 67% of bytes in the average Web pages are images; can be compressed to save bytes. Use lazy loading: only load what is needed for visible on screen elements, later load rest. Avoid “download and hide” or “download and shrink”.
- Non-minified resources: CSS & JS can be compressed to save 70% of transfer sizes. Enable GZIP. Minify the files.
- Too many redirects: DNS lookup + connection + data together take time for each redirect.
- Mobile site speed should be considered a profitable site feature.