Apr 29

11 reasons for your computer running slow and how to fix it

We have all experienced our computer running slow at some point and sometimes the cause is never clear. Sometimes it is simply be the fact the computer is ageing and it is time for it to be replaced and other times a complete reinstall of the operating system can have a dramatic effect on the speed of your computer.

There are other reasons for a computer running slow that don’t require quite such drastic measures as a reinstall or new computer. Around 80% of the computers I see that are running slow are repairable meaning there is no need to spend vast amounts of money on a new computer.

Here we look at the top 11 reasons that your computer may be running slow and how you can fix that slow running computer or laptop.  Work through the suggestions one at a time and hopefully you will find a solution to your problem or at least be pointed in the right direction as to why your computer is running slow.

computer running very slow image1. Malware infection

One of the most common causes that your computer is running slow is a malware infection. A malware infection could do a number of different things to your system including using a lot of system resources leaving very little for legitimate programs.

Some signs of a malware infection are:

  • Icons on your desktop you are not familiar with
  • Longer boot times than usual and a slow running computer
  • Struggling to open more than one program at a time
  • Strange web pages opening


There are many programs out there that can remove spyware but there is one program that stands out when you are wanting to both prevent and remove malware and that is Malwarebytes Anti-Malware which is starting to be considered by mant as important as having anti virus protection

There are also a number of free programs out there that allow you to remove malware infections from your computer. Malwarebytes is probably one of the best free malware removal programs available and is very effective at what it does. You can find instructions on how to use it and links to the program below

Removing spyware and malware

virus infection slow computer

2. Virus Infection

Another very common cause of a computer running slow is a virus infection. These tend to be more serious than a malware infection as they can be destructive and steal personal data or use your computer for malicious purposes. Becasue of the way they run they can also leave your computer running slow and sluggish.


Running your virus scan software will help but people do not realise that sometimes that is not quite enough. Also refer to the solution above and run an anti-malware scan. You need to ensure that your anti virus software is reliable and has high detection rates such as Kaspersky Internet Security which always seems to be in the top 3 of the best anti virus programs

It is also worth running what is called an anti root kit tool to ensure that the virus is entirely gone as sometimes viruses like the DNSchanger virus are not picked up by some antivirus programs.

A very good rootkit removal tool can be downloaded from Kaspersky at the link below.

Kaspersky TDSSKiller tool

3. Corrupt virus protection or wrong/poor security suite

The number of times I come across a corrupt or damaged antivirus or security suite is becoming more and more common and it can be a major culprit for your computer running slow as it struggles to do its job. I’m not sure entirely why except that maybe it is because these programs are now doing more and more to try and protect us and because of that the software has become much more complex. This can happen to any security software and I have experienced it with all of them but it does seem to be more common with Norton and Mcafee (Maybe because more people run these programs) Countless times I have removed the security suite from a slow running computer and the difference after a restart is amazing.


Poor or inappropriate security software is often a  cause for computers slowing down. It could be that the product is poor,  that you have recently downloaded a corrupted update or something you recently installed does not get on with your security suite.  Unfortunately the majority of the time in my experience at least it  tends to be either Norton or Mcafee that cause these problems probably due to their popularity and the fact that they seem to be pre-installed on most new computers.

Although Norton seems to run better nowadyas on newer computers Mcafee for me has let itself down over the last few editions (pre 2012) and is the cause of a lot of problems I find customers have nowadays. The program is it is sluggish, not very good at detecting malicious programs and does more harm than good in some cases as well as being a resource hog. If you are using Mcafee ensure you have the disks to re-install it if needed and then remove it from your computer using the Mcafee removal tool.

Mcafee removal tool

If you notice a significant difference you have you solution… find another security suite. Personally the only one I have ever paid for and rate highly is Kaspersky. Alternativly you could go for free antivirus software. If your system is still the same put Mcafee back on and look at other reasons for your computer running slow.

If you are looking for a security suite recommendation other than the free software I have always found both Kaspersky Internet Security 2012 and Bitdefender Total Security 2012 do the job well with minimum problems and both have excellent detection rates

4. Other corrupt/problematic program file

Sometimes another corrupt program could be sucking up all your resources and leaving nothing for the rest of your computer and this is quite a common cause of a computer running slow. It can be quite a process working out which program it is.


Check what processes are running and what resources they are using on your computer. If you right click on the taskbar at the bottom of your screen you should get a selection of options. Select start task manager.

In task manager you should get a list of programs running and the resources they are using. If you see something that has a reading that is constantly over 70% running in the CPU column when the computer has nothing running than this is likely your culprit. Type the name into Google and it will give you an idea of what the program is. From there uninstall the program and see if that resolves the issue.

If you don’t want to uninstall you can always disable it from starting up via the msconfig. Got to your start button and in the search box at the bottom type msconfig and then press enter. Select the fourth tab that says start-up and then disable the offending program.

Be careful when messing with settings in msconfig.

If you are not sure what program file it is you could try disabling all the items restarting and then enabling a couple. If the computer runs alright enable a couple more until you find the problem program.

5. Heavily fragmented drive

Fragmentation on your drive can mean that it takes the computer longer to find the required files. If your drive is heavily fragmented you will find your computer running slow as it takes longer to locate the files it needs


The software that comes with windows does not tend to be thorough enough and many prefer to use a program called defraggler. You can find links to defraggler below.

Downloading and using Defraggler

Go to Page 2 of 11 reasons for your computer running slow


  1. abieanarna

    Aside from malware always find sometime to defrag your laptop/computer, always update your anti virus. Anyway nice article hoping you’ll feature more.

    1. You are right. Some people say defragging is a waste of time but I find it helps especially if your drive is heavily fragmented

  2. Dolores

    I was very pleased to find this site. I wanted to thank you for this great read!! I am definitely enjoying every little bit of it and i have you bookmarked to check out new stuff you post.

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