Depends where the delay lies. If the font is loaded in such a way that page rendering blocks in all cases then they need to rearrange their code somewhat, but it could be your browser that is broken: unless there is something blocking rendering (the font being loaded synchronously in a static script tag or something) then the browser should render the content using an alternative from the CSS definition or what-ever its default is, and reflow once the font is loaded. While it is extra processing it isn't like modern phones are short of a CPU cycle or few.
Nothing is broken, it's just a design decision: do you show unstyled content or wait until you have everything. See http://paulirish.com/2009/fighting-the-font-face-fout/#updat... for details but the gist is that browsers used to differ (Firefox chose the approach you prefer) but have converged on blocking until the fonts have downloaded.
Currently the only way to get the behaviour you want would be using something like https://github.com/typekit/webfontloader and using CSS to specify a default to be used until the font has transfered:
body { font-family: sans-serif; }
.webfonts-loaded body {font-family: "Open Sans"; }
