Why a Windows PC slows down — and how to fix it

A slow Windows PC almost always has one of a few specific causes. Most "optimizer" apps don't help and some are the problem themselves. Here is what actually works, ordered by cost and impact.

1. See what is eating resources

Press Ctrl + Shift + Esc to open Task Manager. In the Processes tab, look for programs using a lot of CPU, RAM or disk. If the disk sits near 100% constantly, the disk (especially an old HDD) is usually the problem, not the CPU.

2. Trim startup programs

Every app that launches with Windows adds boot time and RAM use. In Task Manager, open the Startup tab and disable what you don't need. You don't have to uninstall useful apps — just stop them from auto-starting.

3. Check free disk space

When the Windows drive is nearly full, the system slows down. Keep at least 10-15% free. Uninstall unused programs and move bulky files (videos, downloads) to another drive. Storage Sense or Disk Cleanup removes temporary files.

4. If you still have an HDD, get an SSD

This is usually the most effective upgrade for an older computer. An SSD cuts boot time and app-launch times dramatically (HDD vs SSD comparison). Back up before swapping.

5. Check the RAM

If RAM in Task Manager is always near full, the computer uses the disk instead of memory and slows down. For everyday work with several browser tabs, 8 GB is usually a sensible minimum and heavy work wants more — but first check what your system supports (RAM guide).

6. Malware and browser extensions

If slowness appeared suddenly or you see strange ads, run a full scan with Windows Security (Microsoft Defender). Review browser extensions and remove ones you don't recognize.

7. Updates and heat

Install Windows and driver updates (especially graphics and chipset). In laptops, dust and old thermal paste cause overheating, which makes the CPU slow itself down; cleaning the fans and vents has a visible effect.

What NOT to do

• "Registry cleaners" and mystery optimizers: riskier than they're worth.
• Disabling Windows services you can't explain.
• Running several antivirus products at once.
• Downloading cracked software — a common source of malware.

If it's still slow

Last order of operations: 1) back up, 2) try Reset this PC to clear the accumulated software, 3) if the machine is genuinely old, a hardware upgrade (SSD, RAM) is the rational end of the road.