We instrumented Chrome and measured the download times: approximately ~1.1% of font loads are longer than 3s. New timeout will help address that 1.1% by using a system fallback.
http://www.igvita.com/2014/01/31/optimizing-web-font-renderi...
http://www.igvita.com/2014/01/31/optimizing-web-font-renderi...
If you want to define own load behavior: use the upcoming Font Load Events API.