Computer Running Slow — Fix Background Apps and High CPU Usage

Overview #

If your computer feels sluggish, freezes for seconds, or takes ages to open programs, the problem is often too many background processes, memory-hungry apps, or overloaded startup programs.
This guide walks you through diagnosing what’s slowing your system — whether it’s Windows or macOS — and how to restore performance with practical, step-by-step fixes.

What you’ll learn

• How to identify what’s using CPU, memory, or disk
• How to disable unnecessary startup programs
• How to clean up background services and scheduled tasks
• How to optimize system power and resource settings

Estimated time: 20–30 minutes
Skill level: Beginner–Intermediate

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Terms and Definitions #

Term	Meaning
CPU Usage	Percentage of processing power currently used by running applications
RAM (Memory)	Temporary storage for active programs and system processes
Disk I/O	Read/write operations between your drive and operating system
Startup Programs	Apps that automatically launch every time your PC boots
Background Services	Hidden processes that run without visible windows, often for syncing or monitoring tasks

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Steps #

Step 1 — Check What’s Using Resources #

Windows PowerShell

Get-Process | Sort-Object CPU -Descending | Select-Object -First 10 ProcessName, CPU, Id

This lists your top CPU-consuming processes.

To view top memory consumers:

Get-Process | Sort-Object PM -Descending | Select-Object -First 10 ProcessName, PM

You can also use Task Manager (Ctrl + Shift + Esc) → Processes tab → sort by CPU or Memory to identify resource-heavy apps.

macOS Terminal

top -o cpu

Lists the top CPU consumers.
Or use:

ps -A -o %cpu,%mem,comm | sort -nr | head -n 10

to list top CPU and memory processes.

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Step 2 — Close or Restart Resource-Hungry Apps #

If you identify a specific app (like Chrome, Teams, or Finder) consistently using over 20–30% CPU:

• Save work and restart the app.
• If it hangs, use:
  • Windows: Stop-Process -Name "AppName" -Force
  • macOS: killall "AppName"

Restarting clears memory leaks and refreshes system handles.

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Step 3 — Manage Startup Programs #

Windows

1. Press Ctrl + Shift + Esc → open Task Manager.
2. Go to the Startup Apps tab.
3. Disable programs that you don’t need every boot (e.g., Spotify, OneDrive, Zoom).

Or via PowerShell:

Get-CimInstance Win32_StartupCommand | Select-Object Name, Command, Location

To remove one:

Remove-Item "HKCU:\Software\Microsoft\Windows\CurrentVersion\Run\AppName"

macOS

1. Go to System Settings → General → Login Items.
2. Disable unnecessary apps under “Open at Login.”

Alternatively, remove persistent launch agents:

sudo rm -f ~/Library/LaunchAgents/*.plist

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Step 4 — Check for High Disk Usage #

Windows PowerShell

Get-Process | Sort-Object IOReadBytes -Descending | Select-Object -First 10 ProcessName, IOReadBytes

If Antimalware Service Executable or SysMain (Superfetch) consume disk constantly, you can temporarily disable Superfetch:

Stop-Service SysMain -Force
Set-Service SysMain -StartupType Disabled

macOS
Use:

sudo fs_usage | grep -i "write"

to view heavy I/O operations.
Spotlight indexing (mds) can spike CPU and disk use temporarily after updates — this is normal and resolves after a few hours.

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Step 5 — Disable Background Apps #

Windows

1. Open Settings → Privacy → Background Apps.
2. Turn off apps you don’t use (e.g., Feedback Hub, Weather, Xbox).

Or disable globally via PowerShell:

Get-AppxPackage | where {$_.NonRemovable -eq $false} | ForEach-Object {Stop-Process -Name $_.Name -ErrorAction SilentlyContinue}

macOS
Disable unneeded helper processes:

launchctl list

Find unnecessary items (like old printer daemons or sync agents), then unload them:

launchctl bootout gui/$(id -u) /Library/LaunchAgents/com.vendor.agent.plist

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Step 6 — Optimize Power and Performance Settings #

Windows

1. Open Control Panel → Power Options.
2. Select High Performance or Balanced (avoid Power Saver).
3. For laptops, ensure cooling policy is set to Active: powercfg /setacvalueindex SCHEME_CURRENT SUB_PROCESSOR PROCTHROTTLEMAX 100 powercfg /setactive SCHEME_CURRENT

macOS
Energy-saving defaults can throttle CPU on battery.
To prevent aggressive sleep throttling:

sudo pmset -a lessbright 0
sudo pmset -a powernap 0

Use with care; this improves responsiveness but may reduce battery life.

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Step 7 — Run System Cleanup #

Windows

cleanmgr /sagerun:1

or

Start-Process -FilePath "cleanmgr.exe" -ArgumentList "/verylowdisk"

Removes temporary and system update files.

macOS

sudo rm -rf ~/Library/Caches/*
sudo rm -rf /Library/Caches/*

Then reboot.

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Step 8 — Update Drivers and OS #

Outdated drivers and OS builds can cause resource leaks.

Windows

DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow

Then open Settings → Windows Update and install all pending updates.

macOS

softwareupdate -i -a

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Step 9 — Restart and Reassess #

After cleanup:

1. Reboot your machine.
2. Run the same PowerShell or Terminal commands from Step 1.
3. Compare CPU, RAM, and disk usage before and after.
   Your system should now idle below:

• CPU: 10–15%
• Memory: 40–60% (depending on open apps)
• Disk: <5% steady use

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Verification #

Check	Command	Expected Result
Top processes	`Get-Process	Sort-Object CPU`
Startup items	Task Manager / Login Items	Only essential apps enabled
Disk activity	Task Manager / fs_usage	Low background I/O
Power plan	powercfg /list	Active plan = Balanced/High Performance

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Conclusion #

A slow computer usually doesn’t need new hardware — it needs fewer background apps and cleaner startup behavior.
By disabling unnecessary processes, clearing caches, and tuning power settings, you can often restore your PC or Mac to near-new responsiveness.
If performance drops again within days, monitor new software installations — they’re often the source of recurring slowdowns.