Mac troubleshooting advice on the internet is largely a decade out of date, and much of it was written for Intel Macs. If your Mac has an Apple chip — M1 or newer — several of the classic tricks no longer exist. Here is what genuinely applies today.
The slow Mac: five real causes
Storage nearly full. macOS needs free space to breathe, and a nearly-full drive slows everything. Go to the Apple menu, System Settings, General, then Storage — it shows exactly what is eating the disk, and the biggest culprits are usually old iPhone backups, mail attachments and Downloads.
Login items. System Settings, General, Login Items. Everything listed there starts when you do. Most of it does not need to.
Spotlight reindexing. If the Mac turned sluggish right after a macOS update and the fan is running, it may simply be rebuilding its search index. Give it a few hours plugged in before doing anything drastic.
The browser. Forty tabs and a handful of extensions will bring any machine to its knees. Activity Monitor (in Applications, Utilities) sorted by Memory will show you in seconds whether this is your problem.
Age. A Mac too old for current macOS eventually falls behind what modern websites and apps expect. Memory on Apple Silicon Macs cannot be upgraded after purchase, so this one has no cheap fix — the general slow computer checklist covers the rest of the thinking.
The one thing not to do
Do not install a "Mac cleaner" or "speed up your Mac" app. That whole category ranges from useless to actively malicious, and the pop-up telling you your Mac is infected is itself the infection. macOS does not need registry cleaning; there is no registry.
When the Mac will not start
First, distinguish no-power from no-picture. Nothing at all — no chime, no fan, no light — is a power problem: try a different charger and cable, and for laptops leave it charging for a good half hour before judging, because a deeply drained battery will not respond immediately.
If it powers on but stops at a logo, a progress bar that never finishes, or a folder with a question mark, the hardware is alive and the system software or drive needs attention.
Safe mode and Recovery — and how they differ by chip
On an Apple Silicon Mac (M1 and later): shut down fully, then press and hold the power button until "Loading startup options" appears. From there you can pick Options to enter Recovery, or hold Shift while selecting your disk to boot into safe mode.
On an Intel Mac: hold Command and R during startup for Recovery, or hold Shift from the chime for safe mode.
Safe mode loads a stripped-down system. If the Mac behaves perfectly there, the fault is software you installed rather than the machine itself. In Recovery, open Disk Utility and run First Aid on the startup disk — this repairs the everyday directory damage behind a surprising share of "won't boot" Macs, and it does not erase anything.
The resets people still recommend
NVRAM and SMC resets apply to Intel Macs only. On Apple Silicon the equivalent housekeeping happens automatically at each restart, so if an article tells you to hold four keys on an M-series Mac, that article is old.
Before you reinstall anything
Reinstalling macOS from Recovery keeps your files, but "keeps" is not a promise worth betting irreplaceable photos on. If the Mac can still be started at all, get a copy of what matters onto an external drive first — and if the drive itself sounds or behaves wrong, stop and get help before repeated boot attempts make it worse.
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