Why is your PC slow? How to find out which component is the problem

"My computer is slow" can have many causes, and the fix depends on which one it is. More RAM won't help if the disk is the problem; reinstalling Windows won't help if it's heat. The effective approach is to measure which resource is maxing out and deal with that. Windows includes everything you need.

#Step 1: Watch Task Manager while it's slow

Open Task Manager (Ctrl + Shift + Esc) right when the PC is sluggish and look at the Processes tab, sorting by each column:

#High CPU

1. Sort processes by CPU and see what's using the most.
2. If it's a program you don't need right now, close it.
3. If it's a system process (for example Windows Update or your antivirus), it may be temporary — let it finish.
4. If an unfamiliar process constantly uses a lot, search its exact name before ending it, and scan with your antivirus.
5. If CPU is always high during normal use, your processor may simply be underpowered for what you do.

#High memory

1. Sort by Memory. A browser with lots of tabs is usually the biggest user.
2. Close tabs and programs you're not using.
3. If memory sits near the maximum during your normal routine, you need more RAM. See how much RAM you need.

#100% disk

Very common on PCs with a mechanical hard drive (HDD).

1. Under Performance > Disk, check whether your system drive is an HDD or SSD.
2. If it's an HDD, switching to an SSD is probably the biggest improvement you can make. See SSD vs HDD.
3. See which process is using the disk: indexing, updates, antivirus or cloud sync are common right after startup.
4. Make sure the drive isn't nearly full. See how to free up disk space on Windows.

#Slow startup

1. In Task Manager, open the Startup apps tab to see what launches with Windows and its impact.
2. Disable what you don't need at startup: game launchers, updaters or chat apps you can open manually.
3. Don't disable anything unfamiliar without looking it up first — audio or touchpad software, for instance.

#Slows down after a while

If your PC starts fine and slows down later, especially under heavy load, suspect heat: the processor throttles to avoid overheating. Clean out dust and check airflow. See CPU and GPU temperatures.

#Other common causes

• Laptop in battery saver or unplugged: switch the power mode to balanced or best performance.
• Outdated or faulty drivers, especially chipset and graphics. See how to update drivers.
• Malware: scan with Microsoft Defender or another reputable antivirus.
• Too many browser extensions: each uses memory and CPU.
• Pending Windows updates: restart to finish installing them.

#What not to do

• Install "optimisers" or "cleaners" that promise to speed up your PC: many do nothing, and some install unwanted software.
• Disable Windows services from old guides without knowing what they do.
• Reinstall Windows as a first resort: it can help, but if the problem is hardware, it'll come back.

#Symptom and fix at a glance

#The bottom line

Before spending money, measure: Task Manager tells you in seconds whether the bottleneck is CPU, RAM or disk. On older machines, an SSD plus 16 GB of RAM usually brings back the snappiness; otherwise, reviewing startup apps, temperatures and drivers fixes most problems.