Why is my computer running so slow?

Common causes of degraded computer performance:

• Resource saturation — CPU, RAM, or disk usage pinned near 100% by background processes, browser tabs, or runaway applications.
• Full or fragmented storage — OS needs 15–20% free disk space to operate; near-full drives (especially HDDs) slow read/write operations.
• Mechanical HDD — Traditional spinning drives are orders of magnitude slower than SSDs; this is the single most common hardware bottleneck.
• Insufficient RAM — Systems with ≤8 GB force disk swapping, causing severe lag under modern workloads.
• Malware or adware — Hidden processes consuming CPU, network, or disk resources.
• Startup bloat — Excessive auto-launching applications at boot.
• Thermal throttling — Dust buildup, failing fans, or degraded thermal paste force the CPU/GPU to reduce clock speeds to avoid overheating.
• Failing hardware — Dying hard drive (bad sectors), degraded RAM, or failing power delivery.
• Pending updates — OS or antivirus scans/updates running in background.

Diagnostic steps:

1. Open the system resource monitor:
   • Windows: Task Manager (Ctrl+Shift+Esc) → Performance tab
   • macOS: Activity Monitor
   • Linux: htop or top
2. Identify which resource (CPU / Memory / Disk) is saturated and which process is responsible.
3. Check storage free space and drive type (SSD vs HDD).
4. Check drive health: wmic diskdrive get status (Windows), smartctl (Linux/macOS).
5. Verify temperatures via hardware monitoring tools (e.g., HWMonitor, lm-sensors).
6. Run a malware scan with an updated scanner.

Standard remedies, in order of impact:

1. Upgrade HDD → SSD (largest single performance gain on older machines).
2. Add RAM if usage regularly exceeds ~80% of installed capacity.
3. Disable unnecessary startup programs and background services.
4. Free disk space; uninstall unused applications.
5. Clean dust from vents/fans; replace thermal paste if unit is 3+ years old.
6. Apply OS, driver, and firmware updates.
7. Restart the machine — resolves memory leaks and stuck processes.

If none apply: The slowdown pattern itself is diagnostic — slow at boot points to startup services; slow only under specific applications points to workload vs. hardware mismatch; progressive degradation over weeks points to storage failure or malware.