Hi,

Making slow PCs faster is part of my daily grind so I have a lot of tips for you here. I may not expand on everything but if you Google whatever words or terms you're not sure of then you will find plenty of hits on them.

There's some good answers here already but to start with I would avoid registry cleaners, they benefit in no way for speed but do pose a risk breaking something. Also avoid any of these "speed up" programs that claim to take total care of your system, they can be ok but ultimately cost more system resources than is worth keeping them around for.

To start with, lets make sure there's no dodgy program on the PC.

Program cleanup

You're gonna wanna check out what programs you have so load up "Add/Remove Program" or "Program & Features". As I mentioned, remove any of these "Speed up" programs and remove any "Toolbars".

Pay attention to the "Publisher" column and any programs where you don't recognise the name of the program or the publisher, be suspicious of it. Typically if you Google the program name, if it's dodgy then you will get a lot of hits of people saying it's dodgy on sites such as "Should I remove it?" so you would then remove it.

Any entries which don't have a "Publisher" entry, be suspicious of and Google it.

Also, as far as your Anti-Virus goes, I have had good experience with a mix of Windows Defender, which is built into Windows 8-10, or Microsoft Security Essentials on 7, and Malware Bytes, the free version, very important. The paid version, which you're offered a trial of during install (don't accept) includes a real-time scanner which is common in almost every Anti-Virus program and having 2 or more real-time scanners on the go massively affects PC performance. The free version has only manual scan, it's a good idea to run this once in a while.

If you don't like Windows Defender, then I think at present Avast and Kaspersky are still excellent alternatives, I personally wouldn't touch McAfee. Just make sure you only use 1.

Virus scan

Ok, next you're gonna wanna run a full scan with Malware Bytes Free and whatever your preferred Anti-virus is, run the scans one after the other, not at same time. Remove or Quarantine whatever it finds, reboot your PC and repeat the process. Keep repeating the process until both scans come up clean, or they keep coming up with the same item/s.

If they are coming up with the same item/s, enable the default Administrator account by copy/paste or typing the following command into an administrative command (Right click command prompt or Powershell and choose "Run as administrator").

net user administrator /active:yes

Then reboot your PC into safe mode and log in as the default Administrator account. This is important because sometimes Virus's hide in a user's directory and so changing the user prevents it from running. Now run both your scans again, clean, reboot into Safe Mode again under Administrator and repeat. Hopefully the 2nd round of scans will come up clean. If they do, reboot normally, back into your own account, and then run the following command in an Administrative Command Prompt

net user administrator /active:no

To return things to the way they were.

OS corruption

If you're on Windows 8-10, these can all be prone to file system corruption which has a massive impact on performance, if you're on Windows 7 skip to SFC repair.

DISM repair

To run a DISM repair, open an administrative command prompt or Powershell (Right click command prompt or Powershell and choose "Run as administrator") and type or copy/paste the following command

DISM /Online /Cleanup-Image /RestoreHealth

This ensures your OS has a working backup to then repair files with during the next command. If it finds any bad files here, it will replace them with a working copy straight from Microsoft, so an internet connection is required.

Sometimes downloading the working files from MS fails, in those cases you will have to manually specify a source by adding the /source switch such as

DISM /Online /Cleanup-Image /RestoreHealth /Source:repairSource\install.wim

Where "repairSource\install.wim" is the location of your installation media (Windows 8/8.1/10 disc or disc image). For example

DISM /Online /Cleanup-Image /RestoreHealth /Source:D:\sources\install.wim

If you don't have your installation media, you can download a copy from Microsoft at

https://www.microsoft.com/en-gb/software...

SFC repair

After running the DISM command, check the OS files by running the following command, also within an administrative command prompt

SFC /scannow

This command will scan your working OS's files, ensuring there's no corruption by replacing any bad files it finds with ones from the backup we just repaired. As the command finishes you will get one of 3 results.

"No corruptions were found" is good.

"Corruptions were found and repaired" is also good.

"Corruptions were found but unable to repair" not good. If this happens, run the command

CHKDSK /R

The PC will then ask for a reboot and will take anywhere from 30m to 4h+ to come back up. After reboot, run DISM command and then SFC command again and hope... Tis not fun fixing after this if SFC still fails.

Cleanup

Now for cleanup, the only program I would recommend is CCleaner Free, just the Cleaner part. You can leave all the default settings, except maybe untick "cookies" for whatever web browser you use. Personally I just cba logging into all my sites again, but up to you.

General tips

For a browser, I like Chrome best but would also recommend Firefox. Just avoid IE at all costs, it's so slow. I even dip into Edge now and again but also find this a little slow. Also check you're browsers Search and Home Page settings. Sometimes malicious programs change your search and home page settings which can open your system up to virus infections so make sure they're both set to something you trust.

If you're on Windows 8-10, do "Restart" your PC once in a while. With Windows 8-10, when you "Shut Down" your PC it doesn't actually fully shut down, Windows saves a small snapshot of what it had running prior to shutdown to make the boot up process quicker, so restarting your PC is the easiest and quickest way of letting Windows fully refresh itself. You can check your PC's uptime in Task Manager (Right click the clock, you will see Task Manager, then "Performance" tab)

Check how much space you have free on your C: drive, make sure it's at least 10% of the total volume of the drive.

Check how much Memory/RAM you have installed on your PC. If it's 2GB or less then it will struggle to multitask with modern programs as they simply expect a bit more these days. You can see how much RAM you have free in Task Manager. If it's full then the system will start getting very slow. You can view the "Processes" to see what's consuming your RAM

If you are on Windows 10, I'd also recommend you ensure you're on the latest version by running Windows Updates. The new versions do come with changes, but nothing that can't be gotten used to and it also comes with massive performance, reliability and security improvments.

If you're on Windows 8, upgrade to 8.1. As with Windows 10, this also comes with many improvements.

And that's about that. By this point, provided there hasn't been any major issues discovered, the machine should be behaving much better now. If there has been a major issue found, your options are to Google your way to a solution which, depending on the issue, can be not so bad or a nightmare. Sometimes, when all else fails, it's just time to backup your files and rebuild the machine. With Windows 8-10 it comes with a "Factory Reset" function built in which can be accessed via "Settings", specific location varies. Always make sure you have a backup of your files prior to doing this though.

p.s...... just realised this is from 2012.. Why is this top of the page? Haha. Oh well, if still on XP, GET A NEW PC! :P