Mozilla’s Firefox browser also offers updates on a regular schedule, but the recovery period after an update is released appears to take as long as a month. That is, users do not download and install updates as frequently as Chrome users do. One reason may be that some users might not use the browser regularly and therefore aren’t seeing and downloading updates. (See Figure 43 on next page.)

We found that Firefox updated its versions about every other week, with the frequency of updates increasing over the course of the observation period. This increase in frequency is reflected in the growth of old Firefox versions within the population. The recovery time is roughly 1.5 weeks, but the times overlap. The population that tries to stay current drops to as little as 30 percent of the user base. At some point, two-thirds of the users have resorted to simply running the browser more than four versions behind the most current one. So, although Firefox is rapidly addressing issues and fixing bugs, the user base is not updating and restarting on the same frequency.

High