Win 10 / 11 · Speed

Fix 'My PC is slow all of a sudden' — the order of attack

When a fast PC suddenly crawls, it's almost always one of four things. Check them in this order.

  • Difficulty Easy
  • Estimated time 15 min
  • Platform Win 10 / 11
  • Last updated
Fix 'My PC is slow all of a sudden' — the order of attack — schematic diagram

Before you start

Medium risk. This change is reversible — you can return to the previous state without professional help or data loss.

Steps

  1. Task Manager → Performance: is the Disk at 100%? (that's your HDD or a dying drive — the answer)
  2. Processes tab sorted by Memory or CPU: is something you don't recognise eating resources?
  3. Did a Windows Update land last night? Sometimes a bad driver updates itself
  4. Run sfc /scannow — corrupted system files present as 'random slowness', not crashes

How to verify the fix

Disk usage is no longer pinned at 100%, the culprit process or update is identified, and overall responsiveness returns.

If this didn't fix it

Disk still pegged at 100% or slowness continues after all four checks — the drive may be failing; run a disk health check.

Next stop: the related fixes below, or start a guided diagnosis.

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