As you probably know, images -- in particular JPEGs -- make up the vast majority of a web page's overall size. The other elements -- text, stylesheets, scripts -- usually account for just a few percent of the total page size. If the file size of images could be reduced by just a few percent, huge speed gains and bandwidth savings could be realized -- for home and office surfers, but more importantly for people on woefully constrained and metered mobile data connections. Mozilla's latest effort, mozjpeg, aims to do that just, by reducing the size of JPEGs by 10% or more.