First off, by faster we do not mean frequency, but rather how fast the update installs on your machine. Ehsan Akhgari has posted an article on Future of Firefox, Updating Firefox in the Background. In this article, Ehsan explains how the current Firefox update process works and what is being done to improve this process.

In order to update itself, Firefox first starts to download an update in the background. When the update is downloaded, Firefox stages it in a directory ready to be applied. The next time that Firefox is about to start up, it checks out the staging directory. If an update ready to be applied is found, Firefox launches the updater program, and applies the update on top of the existing installation (showing that progress bar as it’s doing its job). When the update process is finished, the updater program restarts Firefox. All of this happens as you’re waiting for your browser to start up in order to do what you wanted to do. This is clearly less than ideal.

As a reminder, users CAN opt-out of automatic updates. From Firefox go to Tools > Options… > Advanced > Update (tab), and uncheck Firefox under the Automatically check for updates to:

It is now known at this time when this change will be implemented, but Ehsan is hoping soon.