The common belief that PCs inevitably slow down over time is only partially true. Hardware does not degrade significantly under normal use over 2-3 years. What does happen: software accumulates, storage fills up, thermal paste dries out, and Windows installs layer on layer of startup programs. These are all fixable.
Step 1: Check Storage Health and Capacity
A storage drive that is 85-90% full slows noticeably — SSDs need free space for write operations (over-provisioning), and HDDs fragment data as free space decreases. The symptom: programs that used to load in 2 seconds now take 8 seconds. Solution: clear storage, move files to secondary drives or external storage.
Also check drive health with CrystalDiskInfo (free). A drive showing "Caution" or "Bad" health is failing and will only get worse. Back up and replace.
Step 2: Check Startup Programs
Every application installed has the opportunity to add itself to Windows startup. Over time, 2-3 startup programs become 15-20, and boot times slow accordingly. Open Task Manager (Ctrl+Shift+Esc) → Startup tab. Disable anything that does not need to start with Windows: messaging apps, media servers, update helpers.
Step 3: Check CPU and Memory Usage
In Task Manager, sort processes by CPU usage. Is something consuming unusual CPU? Antivirus running a full scan, Windows Update downloading in the background, a poorly written app consuming 30% CPU doing nothing useful — these all slow the experience. Address the specific culprit rather than the symptom.
Step 4: Check Thermals
If a CPU hits 95-100°C under load, it throttles clock speed to protect itself. The result is exactly what feels like "the PC is slow" — because the CPU is artificially running at a fraction of its rated speed. Re-seating the cooler and replacing thermal paste (which hardens after 3-5 years) often restores full performance.
Step 5: Malware Scan
Malware running in the background consumes CPU and network resources. Run a full scan with Windows Defender and a secondary scan with Malwarebytes (free version). Address any findings before other optimisations.