A slow PC is usually one of five things: too many startup programs, a full disk, outdated drivers, a Windows Update eating CPU in the background, or a machine that just needs a proper restart. This guide covers all five — in order of how likely they are to actually be the problem.
This sounds obvious, but most slow Windows PCs haven't been fully restarted in weeks — they've been sleeping and waking. Sleep preserves your open apps but doesn't clear the memory or apply updates properly.
Click Start → Power → Restart (not Shut down, and definitely not Sleep). Let it come all the way back up before you do anything else.
If it was slow before the restart and isn't slow after — congratulations, that was the problem. Restart every few days as a habit.
Every program that launches at startup adds to boot time and uses background memory all day. Most of them you don't need.
Right-click the taskbar → Task Manager → click the Startup apps tab. You'll see a list of programs with a "Startup impact" column.
Right-click anything rated High impact that you don't actively use at startup and choose Disable. Common safe disables:
Open Task Manager (right-click taskbar → Task Manager) and click the Processes tab. Click the CPU column header to sort by highest usage.
If something is using more than 20% CPU consistently, note what it is:
Then click the Memory column. If total memory is above 80%, you may have too many things open — or you may just need more RAM (that's a hardware call).
Windows slows down significantly when the system drive (usually C:) is more than 85% full. Check by opening File Explorer → This PC.
If you're above 85%, use Windows' built-in cleanup tool:
Win + R, type cleanmgr, press EnterIf the PC is still dragging after a restart, startup cleanup, and disk cleanup — or if you're seeing blue screens, crashes, or error pop-ups — there may be a deeper issue: failing hardware, a corrupted Windows installation, or malware. That's not a DIY fix.
Get remote help now →Outdated drivers — especially graphics and storage drivers — are a common cause of sluggishness and freezing that people never connect to "drivers."
Windows Update: Go to Settings → Windows Update → Check for updates. Install everything. Restart if it asks.
Graphics driver (if you're noticing slowness specifically when switching windows or scrolling): right-click the Start button → Device Manager → expand Display adapters → right-click your GPU → Update driver → Search automatically.
This is a Windows feature that automatically cleans up temp files on a schedule so your disk doesn't quietly fill up again.
Go to Settings → System → Storage → toggle on Storage Sense → click it to configure how often it runs (Monthly is fine for most people).
While you're here, you can also see exactly what's eating space broken down by category — apps, temp files, OneDrive, etc.
Startup programs trimmed, disk cleaned, updates applied. The biggest one is usually startup programs — cutting a few High-impact ones can shave a minute or more off boot time. Make restarting every few days a habit and Storage Sense will keep the disk from filling back up.
If the fixes above didn't move the needle, or you need a dozen machines running smoothly without babysitting them, that's what managed IT is for. We handle updates, monitoring, and maintenance in the background so slow PCs stop being a thing.