We all know (sorta) that APFS will make Macs with SSDs run faster. But will APFS on spinning rust drives make those Macs run slower than they did on HFS+?
Your guess is as good as mine, but I am
guessing (
NOT assuming) any performance change on spinning rust will be unnoticeable in normal use. MacOS Extended (HFS+) is old (1990s), creaky, full of patches, and lacks many features expected of a modern file system. So even though APFS is
optimized for SSDs it is more likely to improve spinning rust performance than degrade it. If iOS 10.3 is any indication the APFS conversion will be invisible unless you go looking for it. Let me reiterate, that is my
GUESS.
That is not to say there won't be some users who will vehemently declare Apple is the evil empire personified and have irreparably damaged/destroyed their HDs and/or Macs with the change to an untested and unknown file system when they could have used the perfectly good MS-DOS.
