Why Is Your Mac Running Slow?
A slow Mac is rarely a hardware problem. The most common causes of sluggish macOS performance are software-based: a full startup disk, too many background processes, outdated macOS, memory-hungry apps, or a cluttered login items list. In 2026, macOS Tahoe introduced new background AI features that can also consume significant CPU and RAM on older machines.
This guide covers all 12 fixes — starting with the fastest, free solutions and progressing to deeper diagnostics. Work through them in order and your Mac should be noticeably faster within the hour.
Fix 1: Restart Your Mac
macOS accumulates memory leaks, stale caches, and zombie processes over hours and days. A restart clears all of it instantly.
Step 1. Click the Apple menu (top-left corner) and select Restart.
Step 2. Uncheck "Reopen windows when logging back in" to start fresh without restoring all previous apps.
If your Mac feels noticeably faster immediately after a restart but slows down again after a few hours, the problem is a runaway background process — jump to Fix 3.
Fix 2: Free Up Startup Disk Space
macOS needs at least 10–15% of your startup disk free to operate normally. Below that threshold, virtual memory, Spotlight indexing, and Time Machine snapshots all compete for the same space — causing severe slowdowns.
Step 1. Click the Apple menu → System Settings → General → Storage.
Step 2. Review what's consuming space. The largest space savers are typically: Applications (uninstall unused apps), Documents (delete large files), and System Data (clear caches).
Step 3. Click Empty Trash if it has undeleted items — this is one of the fastest ways to reclaim gigabytes.
Step 4. In Finder, go to ~/Downloads, sort by size (View → Sort By → Size), and delete everything you no longer need.
Fix 3: Check Activity Monitor for CPU and RAM Hogs
Activity Monitor shows you exactly which processes are consuming your CPU and RAM in real time — no guesswork needed.
Step 1. Press Cmd + Space, type Activity Monitor, and press Enter.
Step 2. Click the CPU tab and sort by % CPU (descending). Any process consistently above 80% is a problem.
Step 3. Click the Memory tab and check the Memory Pressure graph at the bottom. A green graph is healthy; red means your Mac is critically short on RAM.
Step 4. To stop a misbehaving process, select it and click the X button (Force Quit). For a system process you don't recognise, search the process name online before killing it.
Fix 4: Reduce Login Items and Background Apps
Every app that launches at login adds to boot time and steals RAM before you've even opened anything.
Step 1. Go to System Settings → General → Login Items & Extensions.
Step 2. Under Open at Login, remove any app you don't need running immediately at startup. Common offenders: Dropbox, OneDrive, Teams, Spotify, update helpers for software you rarely use.
Step 3. Under Allow in the Background, disable any app that doesn't need background access.
Fix 5: Update macOS to the Latest Version
Apple regularly ships performance improvements and bug fixes in macOS updates. Running an outdated version means you're missing optimisations and potentially running buggy code that consumes extra resources.
Step 1. Go to System Settings → General → Software Update.
Step 2. Install all available updates. If macOS Tahoe is available and your Mac supports it, upgrading often delivers a performance boost on Apple Silicon Macs.
Fix 6: Disable Visual Effects
Transparency, animations, and motion effects look polished but consume GPU resources. On older Macs or those with integrated graphics, disabling them can meaningfully improve responsiveness.
Step 1. Go to System Settings → Accessibility → Display.
Step 2. Enable Reduce Motion and Reduce Transparency.
Step 3. In System Settings → Desktop & Dock, set Minimise windows using to Scale effect (faster than Genie effect) and disable Animate opening applications.
Fix 7: Clear System and App Caches
Corrupted or bloated caches can cause app freezes, slow launching, and general sluggishness without any obvious cause.
Step 1. Open Finder and press Cmd + Shift + G.
Step 2. Type ~/Library/Caches and press Enter.
Step 3. Select all folders inside and move them to Trash. macOS will recreate the caches as needed — you won't lose personal data.
Step 4. Also clear the system cache at /Library/Caches (requires admin password).
Step 5. Empty Trash and restart your Mac.
Fix 8: Reset NVRAM and SMC
NVRAM stores settings like display resolution, time zone, and startup disk selection. SMC (System Management Controller) manages power, thermal management, and performance modes. Resetting both can fix mysterious slowdowns that have no other cause.
Reset NVRAM (Intel Macs):
Shut down your Mac. Press the power button, then immediately hold Cmd + Option + P + R for 20 seconds until you hear the startup chime twice.
Reset SMC (Intel Macs — MacBook with T2 chip):
Shut down. Hold Shift + Control + Option (left side) and the power button simultaneously for 10 seconds. Release all keys, then press the power button normally.
Apple Silicon Macs: There is no NVRAM or SMC reset procedure. Shut down, wait 30 seconds, and restart — this is sufficient.
Fix 9: Check for macOS Background Intelligence Features (Tahoe)
macOS Tahoe introduced on-device AI features that run continuously in the background. On Macs with 8GB RAM or less, these can consume a significant share of available memory.
Step 1. Go to System Settings → Apple Intelligence & Siri.
Step 2. Disable any Apple Intelligence features you don't actively use, particularly Writing Tools and Siri suggestions.
Step 3. Check Activity Monitor for intelligencepolicyd and com.apple.AIWritingService — if these show high CPU, the AI features are your primary culprit.
Fix 10: Optimise Browser Performance
Your browser is often the single largest RAM consumer on your Mac. Each Safari or Chrome tab uses 100–300 MB; 20 open tabs can consume 4–6 GB of RAM.
Step 1. Close tabs you aren't actively reading. Use bookmarks or a read-later app instead of keeping dozens of tabs open.
Step 2. In Safari → Settings → Extensions, disable any extension you don't use daily.
Step 3. If using Chrome, go to Settings → Performance and enable Memory Saver (puts inactive tabs to sleep) and Energy Saver.
Fix 11: Disable Spotlight Indexing Temporarily
After a macOS update or large file transfer, Spotlight re-indexes your entire drive. This process — called mds and mds_stores in Activity Monitor — can max out your CPU for hours and make your Mac feel unusably slow.
Step 1. Open Activity Monitor and check whether mds or mds_stores is at the top of the CPU list.
Step 2. If so, the simplest fix is to wait — Spotlight indexing completes on its own, usually within 2–4 hours on a modern SSD Mac.
Step 3. If you need to stop it immediately: go to System Settings → Siri & Spotlight → Spotlight Privacy and add your startup disk to the privacy list. Remove it after indexing completes to restore Spotlight functionality.
Fix 12: Run Disk First Aid in Disk Utility
File system errors on your startup disk can cause persistent slowdowns that no amount of software optimisation will fix. Disk First Aid checks and repairs these errors.
Step 1. Open Disk Utility (Spotlight → "Disk Utility").
Step 2. Select your startup disk (usually named "Macintosh HD") in the left sidebar.
Step 3. Click First Aid → Run. This is safe to run on a live system for non-startup volumes; for the startup disk itself, boot into Recovery Mode (hold Cmd+R on startup) to run First Aid on it.
When Hardware Is the Real Problem
If your Mac is 5+ years old and all fixes above provide only temporary relief, the underlying hardware may have reached its limits. Key indicators: 8GB RAM with memory pressure constantly red, an HDD (not SSD) as the startup disk, or a CPU that's a generation behind current macOS optimisations. An SSD upgrade is the single highest-impact hardware upgrade for older Macs — it can make a 2018 MacBook feel new again.
Not sure whether it's a software or hardware issue? CloudHouse Technologies offers remote Mac diagnostics — a certified technician will identify the root cause and give you a clear recommendation without guesswork.