Why is my PC so slow? What to check first

1. Something busy in the background

Press Ctrl+Shift+Esc to open Task Manager, choose Processes, and click the CPU column to sort by it; then do the same for Memory and Disk. A program using a large share of any of them while you are not using it is the first suspect: a stuck update, a sync tool scanning your files again, a browser tab playing video, an unfamiliar program you did not install.

Close it and see whether the PC recovers. If it keeps coming back, update, reconfigure or remove the program. Windows Update and Microsoft Defender scans are normal, and finish by themselves.

If you find a program you do not recognise, run a full scan: open Windows Security → Virus & threat protection → Scan options → Full scan.

2. Too many programs starting with Windows

In Task Manager, open Startup apps (called Startup in Windows 10). Everything marked Enabled starts with Windows, slowing the start and holding memory for the rest of the day. Right-click anything you do not need straight away and choose Disable; it stays installed, and still works when you open it. Leave your security software, and the utilities that run hardware you use, such as a touchpad or audio.

3. Windows on a hard drive, or a full drive

In Task Manager, open Performance and select each disk: its type is shown as SSD or HDD. If Windows is on a hard drive, that alone explains a slow start, slow programs and frequent pauses. An SSD handles the small reads Windows makes constantly many times faster, and it is the most effective upgrade an older PC can have.

A drive more than about 90% full slows down too: SSDs need free space to write quickly, and Windows needs room for updates and virtual memory. Settings → System → Storage shows what is using the space, and Storage Sense can clear the safe parts automatically.

4. Not enough memory

In Task Manager, open Performance → Memory while you work as you usually do. If In use sits close to the total, Windows is moving memory out to the drive, which is far slower. 8 GB is tight for Windows 11 with a modern browser, and 16 GB is comfortable for most people.

If you have enough, make sure it performs as it should: memory often runs below its rated speed, or in single channel.

5. The power settings

• In Windows 11, open Settings → System → Power & battery and set Power mode to Best performance. On a desktop it costs little extra power and makes the PC noticeably more responsive. In Windows 10, the same choice is on the slider under the battery icon, or in Control Panel → Power Options.
• Laptops slow down on battery by design. Judge a laptop’s speed plugged in.
• Tweaking tools and some makers’ utilities can cap the processor. In Control Panel → Power Options → Change plan settings → Change advanced power settings → Processor power management, the Maximum processor state should be 100%.

6. Heat

A PC that is quick at first and slows after a few minutes of work is often too hot: the processor slows itself down to stay within its temperature limit. Clean the dust from vents, fans and heatsinks, and make sure every fan spins. How to stress test a PC shows how to confirm it.

7. Drivers and updates

Install waiting Windows updates, and the current graphics driver from NVIDIA, AMD or Intel. On an older installation, the chipset driver from the motherboard or laptop maker’s support page can help too.

8. A failing drive

Long freezes when opening or saving files, with the drive light on, can mean a drive that is failing rather than slow. How to check drive health explains what to look at — and to back up first.

When it is the hardware

If none of this finds anything, the PC may simply be asked for more than its hardware can do. An old processor, too little memory or a hard drive is the usual limit. Before buying anything, measure: a benchmark compared with what the same parts normally score shows whether the PC performs as it should, and which part is the limit. For games, the bottleneck calculator gives a first idea of whether the processor or the graphics card holds them back.

How Bottleneck checks this

Bottleneck checks for everything on this list that Windows can see: programs using the processor or drive in the background, more than 15 programs starting with Windows, Windows on a hard drive, drives more than 90% full, too little memory for what the PC is used for, memory below its rated speed or in single channel, a restrictive power plan or a capped processor, turbo boost switched off, drive health, and a processor that slows down under sustained load.

It then benchmarks the processor, memory, drives and graphics card against what the same parts normally achieve, and ranks everything it finds by what each problem costs you. With Pro, several of the settings can be fixed with one click and undone the same way.