On 6 March 2015 at 10:28, Simon Pieters <simonp@opera.com> wrote: > On Thu, 05 Mar 2015 16:30:23 +0100, Jason Grigsby <jason@cloudfour.com> > wrote: > > In Bruce's article, he quotes Steve Souders as saying that the preloader >> is >> the "the single biggest performance improvement browsers have ever made". >> >> In the link I provided, Andy Davies talks about how Google saw a 20% and >> Firefox a 19% increase in average page speed after implementing the >> preloader. >> > > To be fair, I think those numbers are not entirely relevant for > speculatively loading images per se. The biggest performance improvement is > from speculatively loading other scripts and stylesheets while the HTML > parser is blocked on loading a script. I'm not aware of comparisons of not > speculatively loading only images. > You may be right - those figures are from a while back and pre-loader behaviour has changed over time. Chrome was first to start prioritising scripts but it also has done some prioritisation of visible images in the past, Firefox was a bit later at adopting the same approach. There are a few sites I know off where the scripts being prioritised and the number of them ends up delaying the hero image, so it's not all perfect (as I suspect you already know) Suppose we could built a custom version of Chromium with changed priorities if we really wanted to find out. Cheers Andy
Received on Monday, 23 March 2015 20:27:43 UTC