I used to think that naming things, cache invalidation, and off-by-one errors were the 2 biggest problems in CS, but then I learned about the "sleep/wake" problem and realized it's NP-complete.
With how much trouble I had with trying (and failing) to make my brand new Dell laptop sleep properly and not the "Modern Standby" crap, plus my desktop randomly breaking GPU hardware acceleration in browser after waking up, I would say it's around O(n4) now. Or maybe even O(n!).
Remembering the hours I spent going through KEXTs and bootloader config in ill-fated attempts to set up a Hackintosh fills me now with a kind of horror. Worst of all were the ACPI tables - SSDT and the like.
In contrast to that, running MacOS in a VM is heaven. Figuring out how to pass my iPhone through to Xcode took as long as the initial setup.
