I literally have apps from 2003 on my mac that are powerpc and won’t run. So what? Anything harmful gets segregated out by the OS.
I admit that it tickles me whenever you mention this. Engineers, by nature, have orderly minds. On this forum we often complain about the decades of cruft that are still extant in x86 land, particularly in the ISA, but also within Windows itself. I'm not one of those people who obsessively reinstalls an OS every year to clean out the imaginary detritus, but when I do purchase a new computer, I move everything over by hand because I like to start fresh, while deleting anything unnecessary.
Back during the dark days of being a Windows user, I would typically reinstall Windows every six months or so. I don't know if modern Windows suffers from it, but WinXP would slow down and clog itself up without any assistance from the user. This was particularly bad for gamers, with new drivers being constantly updated, and Microsoft's own updates somehow nuking themselves, never mind the spaghetti code to drive third-party peripherals. One of the many benefits of switching to the Mac was no longer having to worry about the operating system slowly degrading itself.
Not that macOS is always perfect, in that regard. I hung onto Mojave on my 2018 Mac mini until security patches ran dry. When I updated from Mojave to Big Sur, something happened with Safari, after the update, where it was endlessly eating up half the CPU with the anemic i3 housed within my mini. I could never diagnose the issue, other than it was constant after launching Safari, and would only stop eating up 50% of CPU cycles upon force quitting it. I used Time Machine to go back to Mojave. A month or so later, Monterey was released, updated to that, and haven't experienced that issue since. I still have no idea what caused it, but a mysterious leftover from the Mojave install was plaguing Safari, despite the immutable Signed System Volume introduced with Big Sur.
So, while indeed rare, there's always a chance that leftovers, from what I presume to be third-party installs of days gone by, can impact performance after a major macOS version update. I had assumed that it was the remnants of a misbehaving Safari extension, but the only one I use is Adguard for Safari
, and that's regularly updated and hardly an obscure, poorly behaved work of code craft.
Hence, I find it amusing that an accomplished engineer of @Cmaier
's talents may still have 32-bit PPC code lurking somewhere within his M1 Macs, but also irritates the minor OCD I have in regards to the matter. I've got plenty of old crap still sitting on my 2018 Mac mini's internal SSD, such as save files from 32-bit games that I can't run anymore, but those will all be weeded out by hand, whenever I finally move over to the brave new Apple Silicon future.