June 25, 2012, 12:11 PM — Mozilla's new silent updater has not sped up the migration to Firefox 13, according to usage statistics compiled by an Irish metrics company.
Mozilla engineers speculated that an emergency update -- which Mozilla calls a "chem spill" -- that was released June 15 may have slowed the upgrade tempo.
Firefox 13, which launched June 5, was the first upgrade that Mozilla shipped after it seeded users with silent updating as part of the preceding edition, Firefox 12.
"Once a user gives explicit permission to Firefox on their first installation, they will not be prompted again for subsequent releases," Mozilla said at the time in a blog post explaining the new process.
But data from Irish Web metrics company StatCounter shows that Firefox 13 was used less during its first 20 days than was Firefox 12 over a similar span. StatCounter's numbers hint that the silent updating service did not speed up the migration to Firefox 13 or result in more users running that version.
During Firefox 12's first 20 days of availability, its share of all Firefox users increased from 3% on the day of its launch to 63% nearly three weeks later. By the 10th day, 40.1% of all Firefox users were running Firefox 12. The edition cracked the 50% mark 12 days into its release life.
In every instance, Firefox 12 beat Firefox 13.
Firefox 13's share of all Firefox versions climbed from 3% on opening day to just 50.3% by day 20. On its 10th day of availability, Firefox 13 accounted for only 32.2% of all copies of Firefox -- nearly eight percentage points less than Firefox 12 at the same point during its upgrade process -- while the browser didn't break the 50% usage bar until day 19, a week slower than Firefox 12.
It's hard for even Mozilla to say why silent updating didn't do a better job moving users to Firefox 13.
"What is the cause of slow uptake rate since 13.0.1 was released unthrottled?" asked the Firefox release engineering team in a post-mortem meeting last week that focused on Firefox 13's launch.