What’s My Computer Doing? Tools to See Which Apps Are Using Your CPU and Disk

What’s My Computer Doing? How to Check Resource Usage and Stop Slowdowns

Overview

A quick guide to finding what’s using your PC’s resources (CPU, memory, disk, network) and practical steps to reduce slowdowns.

How to check resource usage

• Windows: Open Task Manager (Ctrl+Shift+Esc). Check Processes for per-app CPU, Memory, Disk, Network. Use Performance tab for real-time graphs. Click Open Resource Monitor for detailed I/O and network per-process.
• macOS: Open Activity Monitor (Spotlight → Activity Monitor). Check CPU, Memory, Energy, Disk, Network tabs. Sort by % CPU or Memory.
• Linux: Use top or htop in terminal for live stats; iotop for disk I/O; nethogs for per-process network. GUI: System Monitor (varies by distro/DE).

How to interpret common issues

• High CPU: CPU-bound process (e.g., browser tab, background indexing, crypto miner). Look for processes with sustained high %.
• High memory: Many apps or memory leak; system using swap causes slowdown.
• High disk I/O: Background updates, antivirus scans, or a failing drive causing long read/write queues.
• High network: Large uploads/downloads, sync services, or unwanted connections.
• Thermal throttling: Overheating causes CPU to slow; check temperatures with tools (HWMonitor, iStat Menus, lm-sensors).

Quick fixes to stop slowdowns

1. Kill or restart the offending process from Task Manager / Activity Monitor / kill command.
2. Close unnecessary apps and browser tabs.
3. Disable startup programs (Windows: Task Manager → Startup; macOS: System Settings → Login Items).
4. Check for malware with a reputable scanner (Windows Defender, Malwarebytes).
5. Free up disk space: remove large unused files, empty trash, uninstall apps.
6. Upgrade RAM or switch to SSD if hardware is consistently limiting performance.
7. Update OS and drivers to fix bugs and improve efficiency.
8. Adjust power settings to High Performance when needed (Windows Power Options; macOS Energy Saver).
9. Limit background sync in cloud apps (OneDrive, Dropbox).
10. Check for disk health (chkdsk, SMART tools) and defragment HDDs (not SSDs).

Tools and commands

• Windows: Task Manager, Resource Monitor, Performance Monitor (perfmon), msconfig, chkdsk.
• macOS: Activity Monitor, Terminal commands (top, fs_usage), Disk Utility.
• Linux: top/htop, iotop, nethogs, vmstat, smartctl.

When to seek help

• Persistent unexplained high resource use after killing processes and scanning for malware.
• Repeated crashes, blue screens, or signs of hardware failure.
• If unsure, back up data and consult a technician.

Quick checklist (do these in order)

1. Check Task Manager/Activity Monitor.
2. End the top resource consumer.
3. Scan for malware.
4. Free disk space and reboot.
5. Update software/drivers.
6. Consider hardware upgrades if still slow.

If you tell me your OS (Windows/macOS/Linux), I’ll give exact steps and commands.