Google wants the web to be as fast as possible and it’s been working on a number of initiatives like SPDY, PageSpeed Tools, its hosted libraries and, of course, its Chrome browser. One tool that doesn’t get quite as much press as projects like Chrome and SPDY is mod_pagespeed for the open-source Apache web server.
Another caching-related optimization in mod_pagespeed 1.2 is support DNS prefetching. DNS resolution time, the mod_pagespeed team says, “varies from <1ms for locally cached results, to hundreds of milliseconds due to the cascading nature of DNS.” Pre-resolving DNS requests won’t shave seconds of your site’s loading times, but it could easily save you half a second – and the point of mod_pagespeed is to make many incremental changes that add up to a significantly faster load time.
Here is what this looks like in action:
Also new in version 1.2 is the ability to transcode JPEG images to the progressive JPEG format. This feature was previously available in mod_pagespeed, but users had to manually select it. It’s now a ‘core’ filter.
The team also notes that mod_pagespeed can now proxy and optimize resources from trusted domains. This, they say, “enables you to optimize resources even from servers that don’t run mod_pagespeed” and will also provide performance benefits for sits that run SPDY.