Why Is My Computer Running Slow? 7 Common Causes (and Easy Fixes)

If you've ever searched "why is my computer running slow?", you're not alone. It's one of the most common IT support questions from small businesses.

A slow computer can reduce productivity, cause frustration, and waste valuable working time. The good news? Many performance problems can be fixed without replacing your device. Common causes include too many startup programs, insufficient RAM, limited storage space, outdated software, malware, and ageing hard drives.

1. Too Many Startup Programs

Many applications automatically start when you switch on your computer. The more programs that launch in the background, the slower your PC can become.

Fix: Disable unnecessary startup apps and restart your computer regularly.

2. Low Disk Space

A nearly full hard drive can significantly affect computer performance. Temporary files, downloads, and old software can quickly consume storage space.

Fix: Delete unused files, empty your recycle bin, and uninstall programs you no longer need.

3. Not Enough RAM

RAM (Random Access Memory) helps your computer handle multiple tasks at once. If you regularly run Microsoft 365, Teams, Chrome, and other applications together, your PC may struggle if memory is limited.

Fix: Close unused applications or consider a RAM upgrade.

4. Outdated Software

Windows updates and software updates often include performance improvements and security fixes. Running outdated software can make your computer slower and less secure.

Fix: Keep Windows, Microsoft 365, and your applications up to date.

5. Malware and Viruses

Malware, spyware, and unwanted software can run quietly in the background, consuming system resources and slowing everything down.

Fix: Run a security scan and ensure your antivirus software is active and up to date.

6. Too Many Browser Tabs

Modern web browsers use a lot of memory, especially when multiple tabs are open.

Fix: Close tabs you're no longer using and remove unnecessary browser extensions.

7. Your Hard Drive Is Ageing

If your computer still uses a traditional hard disk drive (HDD), upgrading to a solid-state drive (SSD) can dramatically improve boot times and overall performance.

Fix: Consider upgrading to an SSD before replacing the entire computer.

How to Speed Up a Slow Computer

Here are some quick ways to improve computer performance:

·         Restart your PC regularly

·         Remove unused software

·         Install Windows updates

·         Free up disk space

·         Run a virus scan

·         Disable startup programs

·         Upgrade RAM if needed

·         Upgrade to an SSD

Need Help Speeding Up Your Computer?

Before spending money on a new device, it's worth finding out what's causing the slowdown. In many cases, a simple upgrade or computer health check can prolong the life of your PC.

If your business computers are running slow, get in touch with Westway IT. We'll help identify the issue and recommend the most cost-effective solution to get your team working faster.

John Fisher

Managing Director, Westway IT

John is the founder of Westway IT and works directly with small businesses across Gloucestershire to keep their IT secure, productive and stress-free.

With a BSc in Computer Science and hands-on experience supporting businesses from 1 to 40 users, he specialises in cyber security, Microsoft 365 and business automation.

An award-winning MSP owner and active member of the global IT community (including GTIA), John focuses on solving real business problems, not just technical ones.

Published: 10 November 2026 | Last Updated: 10 November 2026