Why Is My Mac Running So Slow? The Complete Troubleshooting Guide

A slow Mac can affect everything from basic browsing to everyday productivity. This guide walks through the most common causes and simple steps you can take to improve performance, whether you’re at home or running a small business.

Why this happens

A Mac that feels slow is usually dealing with a combination of small issues rather than one major fault. Over time, apps, files and tasks running in the background can begin to affect performance. For most users, the cause is something simple, low storage, too many apps running, or browser overload, rather than a genuine hardware problem.

Common signs your Mac is running slow

You might notice one or more of the following:

Common signs include apps taking longer to open, delays when switching apps, the spinning colour wheel appearing regularly, browser tabs freezing or reloading, and slow startup or shutdown.

If these issues appear gradually, it usually points to a manageable problem rather than hardware failure.

The most common causes

Too many apps running at once. Every open app uses memory and processing power. Even apps running quietly in the background can slow things down.

Low available storage. macOS needs free space to operate efficiently. As a general rule, try to keep at least 10-20% of your drive free, once it gets too full, performance drops quickly. (If storage is your main issue, see our companion guide on freeing up disk space on your Mac for a proper deep-dive into exactly how to do this.)

Browser overload. Multiple tabs, extensions and media-heavy websites can use a lot of memory and processing power.

Apps that open automatically. Login items can keep running in the background without you noticing.

Outdated macOS or apps. Older software can become inefficient over time, especially as newer updates improve performance and compatibility.

Step by step troubleshooting

Start with the simplest steps first. You can often improve performance quickly without making major changes.

• Restart your Mac to clear temporary problems and refresh the apps and services that are running. Open the Apple menu and select Restart.
• If you haven’t restarted in a while, this alone can make a noticeable difference.
• Check what is using resources. Open Applications, then Utilities, and launch Activity Monitor to see which apps are using the processor and memory.
• Look for apps using a high percentage of the processor or memory. If something looks unusually high, quit that app and see if performance improves.
• Free up storage space. Open the Apple menu, choose System Settings, click General in the sidebar, then click Storage.
• Common ways to free space: delete large files or old downloads, empty the Trash, remove unused apps, or move photos and files to external storage or iCloud.
• Reduce login items. Open System Settings, select General, then choose Login Items.
• Remove anything you don’t need starting automatically, this can improve both startup time and overall performance.
• Clean up your browser by closing unused tabs, removing unnecessary extensions and restarting it. If the problem continues, try another browser.
• Install updates. Open System Settings, select General, then choose Software Update. Install any available updates and restart if required.

What to avoid

Steer clear of apps that claim to “clean” or “speed up” your Mac automatically. These tools rarely help, and some cause problems by deleting the wrong files or interfering with macOS itself. (We cover exactly why these apps don’t work, and what to do instead, in our companion piece on Mac performance myths.)

When the problem might be more serious

If your Mac is still slow after trying these steps, it may indicate something deeper. Possible signs include constant overheating, loud fan activity even when idle, apps crashing regularly, or persistent system lag even after a restart. These can point to an ageing Mac, a storage fault or a software problem that needs proper investigation.

Most slow Mac issues come down to storage, background activity, or everyday usage habits. With a few simple checks, you can often restore performance without replacing your device. If your Mac is still not performing as expected, Your Mac Support & Setup team can help diagnose the issue and get everything running smoothly again, whether it is one home Mac or all the Macs in a business.