Why?
Big pages require a possibly high cost and a long waiting time in many mobile networks. For instance, on many mobile networks, downloading 100KB worth of data takes as long as 1 minute.
How?
Focus on the piece of information that you want to deliver. Scale down images to a reasonable size. Remove images that are not essential to the layout of the page. Make sure to separate CSS styles defined for screen and handheld media types so that only relevant CSS styles are downloaded by most devices.
Where?
Triggered by the resource under test.
More information
Severity: critical
Most mobile devices will not be able to render (part of) the page or will not be able to render the page in a reasonable time frame. Critical failures should be addressed first!
Category: Keep it small
Smaller sites make users happier by costing less in time and money.
Best practice:
Ensure that the overall size of page is appropriate to the memory limitations of the device.