Computer running slow? Here's what to try first

The computer used to feel fine. Now every click waits. Tabs freeze. The fan sounds like it is working overtime. You start wondering if you need a new machine. Most of the time, you do not. Start with what is using the CPU, memory, and disk right now. That mix is normal.

• Open Task Manager. Press Ctrl+Shift+Esc. Sort by CPU, then memory, then disk. Close the thing sitting at the top if you do not need it.
• Restart properly. Not sleep. Not hibernate. A real restart. That clears leftover processes that have been sitting there for days.
• Trim startup apps. If it is only slow when you first log in, too many programs are launching at once.
• Leave some disk free. A drive that is almost full makes Windows hunt for space on every save.

Give it five to ten minutes after the restart. If it feels normal again, you were dealing with a temporary hog. If it is still sluggish, something is sticking around: startup bloat, a full drive, malware, or hardware that has hit its limit. Computer Support Scientist covers homes and offices across NSW. Sydney can start with computer help across Sydney. Central Coast homes can use computer help on the Central Coast.

Fast checks, in order

Work through these in order. Each one takes a few minutes. Jumping to a new PC is how people miss a browser with forty tabs open.

1. Restart properly. Click Restart, not Sleep or Hibernate. That clears RAM and resets background tasks that have quietly eaten resources since you last rebooted.

2. Close unused apps and browser tabs. A browser with a pile of tabs can use more memory than half a dozen desktop programs. Chrome has its own Task Manager on Shift+Esc. Firefox has about:performance.

3. Clear cache and unused extensions. Old cached files and a forgotten extension are easy to miss. Clear the cache in your browser settings, then disable anything you do not recognise.

4. Find one obvious hog. Open Task Manager and look for a single process sitting above 50% CPU or disk. Often it is a tab playing video, a sync client indexing files, or an update running in the background.

5. Try a second restart if the first did not help. Windows sometimes needs two reboots to finish an update or clear a stuck service. If it is still slow, boot into Safe Mode: hold Shift while you click Restart, then Troubleshoot, Advanced options, Startup Settings. If it feels fine there, the cause is software, not a dying part.

Pro Tip: If it is only slow when you first log in, look at startup apps before you blame the hardware.

How to see what is slowing it down

Task Manager is the first stop. The Performance tab tells you almost everything at a glance.

CPU. A graph sitting near 100% with no obvious app on the Processes tab often means a runaway process or malware. Sort by CPU and see what is actually using it.

Memory. If usage sits above 80% at idle, you likely do not have enough RAM for what you run, or something is leaking memory over time.

Disk. This is the one people miss. A drive pinned at 100% while CPU and RAM look normal usually means Windows Update, an antivirus scan, or Search indexing a slow hard drive.

Network. If programs feel stuck but resource use looks fine, background syncing or a misbehaving app can flood the connection.

For a closer look, search for Resource Monitor and open it. That shows which file or process is hammering the disk. Search for Reliability Monitor if the slowdown started suddenly. It gives a timeline of crashes, failed updates, and driver changes.

• Persistent 80 to 100% CPU with no clear app: check for malware or a stuck background task
• Disk pinned at 100%: check Windows Update, run a scan, or test the drive's health
• Memory stuck above 80%: fewer apps, or more RAM
• Slowness gone in Safe Mode: a startup program or driver, not the hardware itself

Pro Tip: Watch Task Manager while you do the slow thing, not at idle. A video call or a big spreadsheet shows the bottleneck. An empty desktop hides it.

Could malware be the cause?

Malware and cryptomining scripts can max out CPU or disk with almost no other sign. If the computer is slow, the fans are loud, and you did not open anything demanding, rule this out early.

• Run a Windows Security quick scan first. Search for Windows Security in the Start menu.
• Follow with a full scan if the quick scan finds anything, or the slowness still has no explanation. That can take a while on a full drive.
• A second-opinion scan with Malwarebytes can catch adware that Windows Security sometimes misses. Use it as a one-off scan. Do not leave two real-time antivirus tools running at once. They fight each other and make the PC slower.

Microsoft lists malware scanning as a core performance step because infections are a common, fixable cause of a sudden slowdown.

Trim startup programs

A machine that takes forever to boot, then feels fine, is almost always drowning in startup programs.

Open Task Manager, then Startup apps. Disable anything you do not need the moment you log in. Leave antivirus, and leave the touchpad or graphics helper alone.

Also check Settings, Apps, Startup. Some apps register there instead of Task Manager. Then review Installed apps for background permissions. Plenty of apps keep running after you close the window.

Pro Tip: Do not disable a process you do not recognise until you search the name. Some of those entries belong to security software or the trackpad.

Free up storage without breaking anything

A drive running near capacity forces Windows to work harder for temporary files. That alone can make a fast computer feel sluggish overnight.

• Leave about 10 to 15% free on a spinning hard drive, and closer to a quarter free on an SSD. Solid-state drives slow down as they fill.
• Use Storage Sense under Settings, System, Storage. It can clear temp files and empty the recycle bin on a schedule.
• Run Disk Cleanup for a one-off sweep. Check Downloads and old installer files. Those hide more than people expect.
• Defragment only a traditional hard disk. Never defrag an SSD. Search for Optimise Drives instead. That runs TRIM, which is the right maintenance for solid-state storage.

Pro Tip: Pause OneDrive or other cloud sync while you are diagnosing. Syncing can quietly use disk and network at the exact moment you are trying to see what is wrong.

Updates and drivers before you blame the hardware

A slowdown that appeared out of nowhere is often a recent Windows update or a tired driver, not a failing part.

• Check Settings, Windows Update. Install anything pending, including optional driver updates listed separately.
• Open Device Manager and look for a warning icon, especially on graphics and storage.
• Create a restore point before you update a major driver. If the new one makes things worse, right-click the device, Properties, Driver, Roll Back Driver.

If a new driver or update lines up with the day it got slow, that is your clue. Reliability Monitor is the easy way to see that timeline.

When the hardware is the real limit

Sometimes you do everything right and it is still slow. That is the signal the hardware has hit a genuine limit.

• RAM sitting above 80% during normal use, not just with twenty tabs open, means you do not have enough memory for how you actually work.
• A hard disk pinned at 100% even after cleanup and a malware check usually means the drive itself is the bottleneck, or it is starting to fail.
• A CPU that is several years old can struggle with everyday video calls and spreadsheets. Modern software simply asks more of it.

The order of impact matters. Swapping a spinning hard drive for an SSD is usually the change people feel most: boot times, app loading, even opening File Explorer. Extra RAM comes next if you juggle browsers and documents. A CPU upgrade on its own rarely makes sense, because it often means a new motherboard as well.

16GB of RAM is a sensible baseline for everyday use in 2026. If the laptop has soldered RAM and you cannot add more, that is a real limit, not a setting you missed. At that point a replacement can make more sense than another round of software tweaks. Newcastle and the Hunter can start from computer help in Newcastle.

Heat is the quiet one. Years of dust in the vents can throttle the CPU so it runs well below its rated speed. The machine feels slow even when Task Manager looks calm. A careful clean can bring that back. Do not blow canned air into a laptop you have never opened if you are unsure. Dust plus fans is easy to get wrong.

When to stop and call

DIY covers most sluggish PCs. A few signs mean stop guessing.

• The drive fails a S.M.A.R.T. health check, or CHKDSK reports bad sectors
• The CPU runs hot and slow, often from dust that has built up for years
• Unknown processes come back after you remove them
• Crashes or freezes with no consistent trigger

Have this ready when you call:

• Whether CPU, memory, or disk was maxed out in Task Manager
• When it started, and what changed just before
• Whether it is slow at login, all day, or only in one app
• Whether you already ran a malware scan and a restart

Ask what the diagnosis involves, and whether a remote look will do before anyone visits. If the files matter, say so first.

What we see on visits

Most slow-PC visits end the same way: a startup clean-up, an SSD swap, or a dust-out. Startup bloat is the common one. Dozens of quietly launching apps nobody remembers installing. An SSD on an old hard-disk machine is the change people notice most. A five-minute boot becoming fifteen seconds is a real thing we see.

Hardware replacement is rarer than people expect, but it is real. A laptop with soldered 4GB of RAM cannot be fixed with software. We start with what Task Manager shows, then we talk through upgrades only if the numbers support them. Work is approved before it starts.

PC Scientist can help when it stays slow

Some of these checks take five minutes. Others hide under a sealed laptop or a drive that is starting to fail. That is a fair reason to stop. Computer Support Scientist can look with you, remotely first if that is enough, or onsite if the hardware itself is the problem.

Tell us whether it is slow at login, all day, or only in one program. Mention what Task Manager showed if you looked. We will say whether a remote session will do, or whether a visit makes more sense. Call 0493 563 381, or pick your area below.

Sources

These pages help when you want the maker's own steps:

• Tips to improve PC performance in Windows - Microsoft
• Computer running slow? Intel tech tips
• How to speed up a slow PC - HP

If a vendor page tells you to defrag an SSD, skip that step. Use Optimise Drives instead.