By David Support · November 12, 2026 · 3 min read
A computer that has become slow is one of the most common problems we see, and many causes are easy to fix yourself. Work through this list in order. It goes from free and safe to the point where it is time to call someone.
Key takeaways
- Most slowdowns come from too many startup programs, a nearly full drive, malware or an old hard drive.
- Back up your files before you change anything important.
- Replacing a spinning hard drive with an SSD is often the single biggest speed-up.
- If nothing here helps, free diagnostics will tell you whether it is the drive, memory, software or something else.
1. Restart it properly
It sounds obvious, but a computer that has run for weeks without a full restart collects memory leaks and stuck processes. Restart (not just close the lid) and see if it behaves. On Windows, use Restart rather than Shut down, because Fast Startup can keep old problems alive.
2. Check how full your drive is
When a drive is nearly full, the system has little room to work. Try to keep at least 15 to 20 percent free. On Windows open Settings → System → Storage; on a Mac open Apple menu → About This Mac → Storage. Delete or move large files, empty the recycle bin and uninstall things you do not use.
3. Cut down what starts with the computer
Every program that launches at startup uses memory and processor time all day. On Windows press Ctrl + Shift + Esc, open the Startup tab and disable anything you do not need. On a Mac use System Settings → General → Login Items.
4. Install updates
Operating system and driver updates fix performance bugs as well as security holes. Run Windows Update or macOS Software Update, then restart. If updates keep failing, that is itself a symptom worth looking at.
5. Scan for malware
Adware, browser hijackers and cryptominers quietly use up resources. Run a full scan with Windows Security (Microsoft Defender). On a Mac, look at your browser extensions and your Applications folder for anything you did not install. Pop-ups, a changed home page or search engine, and fans running while nothing is open are classic signs.
6. Tidy your browser
A browser with dozens of extensions and tabs can slow the whole machine. Remove extensions you do not use, clear the cache, and close tabs you are not reading.
7. Check for overheating
A hot computer slows itself down to protect itself. Dust in the vents, a blocked fan or old thermal paste are common causes, especially on laptops. Use a hard, flat surface, never a bed or a sofa. If the fan is always loud and the case is hot, a professional clean often brings back the speed.
8. Look at the drive itself
If your computer still has a spinning hard drive, it is almost certainly the bottleneck. Moving to a solid-state drive (SSD) can make an older computer feel new, and is one of the best-value upgrades there is. A drive that is failing can also cause freezes and slow file access, so back up first.
9. Consider more memory
If your computer has 4 GB of memory, it will struggle with modern websites and apps. 8 GB is a sensible minimum today, and 16 GB is more comfortable for heavy use. Not every laptop can be upgraded, so check before buying.
10. Back up, then reset as a last resort
If the system is cluttered beyond repair, a clean reinstall of the operating system often fixes it. This erases your settings and programs, so back up your files first. Read our backup guide.
When to get help
Call someone if you hear clicking from the drive, see blue screens or random restarts, smell burning, or if you cannot afford to lose the files on it. David Support diagnoses computers for free and tells you exactly what it needs.
Frequently asked questions
Why is my laptop suddenly slow?
A sudden slowdown usually points to a recent update, new software, malware or a drive that is nearly full or failing. Checking startup programs, free space and a malware scan are the quickest first steps.
Will adding memory or an SSD speed up my computer?
Often, yes. An SSD upgrade helps most when the computer has an old spinning hard drive. More memory helps when you run many programs or browser tabs at once.
Is it worth fixing a slow computer or should I buy a new one?
If the hardware is otherwise healthy, a cleanup or an SSD or memory upgrade is usually much cheaper than a new computer. A free diagnosis will tell you which makes sense.
Free diagnostics
We find the problem at no cost and explain it in plain English.
$39–$75 per hour
Straightforward hourly rates. You approve the cost before work starts.
No fix, no charge
If we cannot fix it, you pay nothing. Repairs carry a 30-day warranty.
