Apart from the built-in PDF viewer, fresh features include a browser debugger, quicker startup and additional browser development tools for add-on developers.
The 10MB update will replace the browser download for new installers, but is also available online or on Google Play as a free download for new customers.
Firefox mobile sites now allow users to personalise their browser with extra themes and additional Chinese language functions.
Added processors also enables the browser use to load on 15 million smartphones.
HumanIPO reported earlier this month on two Firefox OS-based smartphones made available to developers.