Firefox 15 has a new code that stops add-ons from leaking memory that drastic improvements in performance, the developer have also patched 31 vulnerabilities, 23 of them dubbed "critical," the top-most threat in Mozilla's system. Five were labeled "high" and three were pegged as "moderate."
Feature changes to Firefox 15 included new support for SPDY v3, the Google-designed protocol that promises faster and more secure page loading, and the final installment of the browser's silent update service. Firefox 15 applies regularly-scheduled and emergency updates entirely in the background so that the user no longer sees an update installation progress bar.
Called "background updating" by Mozilla, the process is invisible to users because the update is automatically applied, then staged in a different directory or folder than the current copy of the browser. The next time Firefox is launched, the staged directory swaps places with the active directory