A MacBook running slowly is one of the most common complaints we hear, and it's almost never the machine's fault alone. Storage filling up, too many apps competing for RAM, an aging drive, and runaway background processes all contribute. The good news is that most causes are identifiable in minutes, and fixing them doesn't require a technician.
Start with Activity Monitor
Before touching any settings, open Activity Monitor (Applications > Utilities > Activity Monitor). This tool shows you exactly what's consuming your CPU and memory in real time. Sort the CPU column from highest to lowest. If a single process is sitting above 80% and you don't recognise it, that's your first lead.
Switch to the Memory tab next. At the bottom you'll see a "Memory Pressure" graph. Green means you have headroom. Red or persistent yellow means macOS is running out of physical RAM and writing to your storage drive as overflow. That alone can make a MacBook feel like it's wading through sand.
Check your storage
macOS needs free space to function. It uses your drive for virtual memory, Time Machine snapshots, app caches, and temporary files. When a drive is more than about 85% full, performance drops noticeably. When it hits 95%, the machine can slow to a crawl.
Go to Apple menu > System Settings > General > Storage to see what's taking up space. The four biggest offenders are usually: large video files, duplicate photos, old iOS backups stored in Finder, and downloaded files that never got deleted. Clear those first before anything else.
If your MacBook has an older spinning hard drive rather than an SSD, that's a significant performance bottleneck on its own. Swapping to an SSD is one of the most cost-effective upgrades available on older models. If you're unsure which you have, Apple menu > About This Mac > More Info > System Report > Storage will tell you.
Manage login items and background apps
Every app that launches at startup consumes CPU and RAM before you've even opened a browser tab. On macOS Ventura and later, go to System Settings > General > Login Items to see what's loading on boot. Remove anything you don't need running all the time.
Common culprits include Dropbox, Google Drive, Spotify, creative suite helpers (Adobe updaters, Creative Cloud), and utilities from hardware peripherals you no longer use. Disabling 4 or 5 of these can shave 30 seconds or more off your startup time and free up a noticeable chunk of RAM.
Reset the SMC and PRAM
The System Management Controller (SMC) handles power management, fan speed, thermal thresholds, and several other low-level functions. A corrupted SMC can cause a MacBook to run hot, throttle performance unnecessarily, or behave sluggishly even when resources look fine in Activity Monitor.
On Intel MacBooks, shut the machine down, hold Shift + Control + Option on the left side of the keyboard, then press the power button for 10 seconds. Release all keys, wait a moment, and restart. On Apple Silicon Macs (M1 onwards), simply shut down and wait 30 seconds before restarting. The SMC is handled differently on the new chips and doesn't require the key combination.
Resetting PRAM (or NVRAM on newer models) handles display resolution, speaker volume, startup disk selection, and kernel panic logs. On Intel Macs, restart and immediately hold Command + Option + P + R for about 20 seconds until you hear the startup chime twice. Apple Silicon Macs reset NVRAM automatically on startup when needed.
Update macOS and your apps
Running an outdated version of macOS is a performance issue, not just a security one. Apple routinely ships updates that improve memory management, fix kernel-level bugs, and patch inefficient code paths in core system processes. Check System Settings > General > Software Update and install any pending updates.
Third-party apps matter too. An outdated version of Chrome, for example, can consume 2 to 3 times the RAM of the current release. Keep the App Store set to auto-update, and manually update anything installed outside the App Store through the app's own updater menu.
Check for malware
Macs aren't immune to malware, and adware or cryptomining software will peg your CPU at 100% while running silently in the background. If Activity Monitor shows a process you don't recognise consuming significant resources, search its exact name before force-quitting it. If it looks suspicious, run a scan with a trusted tool like Malwarebytes for Mac (the free version covers manual scans).
For a broader look at whether your machine might have been compromised, our guide on how to tell if your computer has a virus or malware covers the warning signs across both Windows and Mac.
Consider a hardware upgrade or repair
If you've worked through every software fix and the MacBook is still slow, the hardware itself may be the limiting factor. RAM can't be upgraded on Apple Silicon models (it's soldered to the chip), but on many pre-2019 Intel MacBooks the RAM is upgradeable. Storage is a different story: on most pre-2017 models an SSD swap is straightforward, and the speed difference versus a spinning drive is dramatic.
Thermal paste between the CPU and heatsink also degrades over time. On machines more than 5 years old, dried-out thermal paste can cause the processor to throttle its own clock speed to avoid overheating, which looks exactly like a slow machine. Our article on laptop overheating explains the warning signs and what a reapplication involves.
If you're not sure whether a repair is worth the cost, our breakdown of computer repair costs in Australia gives realistic figures for the most common MacBook jobs, including SSD upgrades and thermal paste services.
When to wipe and reinstall macOS
A clean macOS reinstall is a last resort, not a first step. But if the machine has accumulated years of software, failed installs, and misconfigured system extensions, starting fresh can recover performance that no amount of tweaking will match. Before doing anything, make sure your data is fully backed up. Time Machine is the simplest option, but a full clone to an external drive gives you a faster recovery path if something goes wrong.
To reinstall, restart your Mac and hold Command + R on Intel models (or hold the power button until you see startup options on Apple Silicon). Select Reinstall macOS from the Utilities window. You don't need to erase your drive to do this. A reinstall over the top of an existing system replaces system files without touching your user data.
That said, a full erase and reinstall clears everything and genuinely starts clean. If you go that route, check our guide on how to back up your computer before you begin.