I’m all for timely updates to macOS, but if you’re keeping a Big Sur system up-to-date you’ll know what I mean when I say you can have too much of a good thing. If you’re back on Catalina or earlier, the reason that your friends using Big Sur go quiet for one day every couple of weeks is that they’re updating.

This has been particularly severe over the last six weeks: we got Big Sur 11.2 on 1 February, 11.2.1 on 9 February, 11.2.2 on 25 February, 11.2.3 on 9 March, and later this month we’re likely to get 11.3. It’s not just the frequency that has us whingeing either: particularly if you’ve got an M1 Mac, these are big updates, ranging in size from 3.1 to 4.2 GB.

Subjectively, we think Big Sur is proving far heavier on updates. Here are some figures to provide objective evidence to your feelings. First, let me briefly review the update history of each of the last three versions of macOS.

macOS Mojave

This started well, with just one Supplemental Update (SU) added prior to 10.14.6, but ended rather messily, with no less than three SUs to its last version, 10.14.6. Smallest updates were a little less than 1 GB, and the largest only 3 GB. Total updates released after 10.14 amounted to 21.53 GB in 10 updates.

macOS Catalina

Catalina had many more SUs, and exceptionally ran to 10.15.7, and even that had an SU. Its smallest update, after an SU for the initial release, was 1.2 GB, and the largest was 4.5 GB for 10.15.1. Total updates released after 10.15 amounted to 32.17 GB in 12 updates.

macOS Big Sur

With its change in version numbering system, macOS 11 has hopefully replaced the Supplemental Update with patch releases like 11.2.2. Although we haven’t yet reached 11.3, there have already been 6 updates to the initial 11.0 release, and there are marked differences between Intel and M1 Macs. The initial release for Intel Macs was 11.0.1, which was an update for early M1 models, which came with 11.0 pre-installed, and required immediate updating to 11.0.1. Sizes of updates are also different: for Intel Macs these have ranged from 2.3-3.27 GB, for M1s 3.1-4.2 GB. Total update size delivered so far has been 13.86 GB in 5 updates for Intel Macs, and 22.27 GB in 6 updates for M1 models.

Cumulative sizes

The clearest picture is seen in a graph of cumulative update size against minor version number, below. For this, the total size of updates for each minor release is the sum of all patches/SUs before the next minor release. Thus, the size of Catalina 10.15.4 is 3.42 GB (10.15.4 update) plus that of 10.15.4 SU (1.38 GB).

The lines shown are fitted using least-squares linear regression, and fit the cumulative totals surprisingly well. According to their equations:

• Mojave’s minor versions required a total of 3.5 GB of update per version.
• Catalina’s required 4.6 GB per version, and extended to 7 rather than 6 minor versions.
• On Intel Macs, Big Sur’s updates have already required 10.6 GB per version.
• On M1 Macs, Big Sur has required 14.1 GB per version, and the cumulative total up to 11.2 has already exceeded that for the whole of Mojave.

Projections

If Apple were to issue no further patches to Big Sur, only minor updates terminating at 11.6, the minimum total update size for the whole cycle would be 23 GB for Intel models, and 35 GB for M1s. However, at the present rates of growth Big Sur would be expected to require a total of 56 GB for Intel and 78 GB for M1 models.

If you think those sound grim, consider Apple’s requirements: for every million M1 users, Apple’s software update servers would have to deliver 78 million GB, that’s 78 petabytes. That’s a small proportion of global ‘fixed’ internet traffic, which is around 180,000 petabytes per month, but it’s a terrifying amount for individual users.

Didn’t Apple promise that updating Big Sur was going to be faster and easier? It ain’t from where I’m sitting.