One of the things I'm asked time and time again is to help speed up a computer. The conversation normally goes something like "my computer / the kids computer used to be much quicker but for some reason its now very slow, what can I do".

Why does my computer slow down ?

Computers have 3 main resources that enable them to function, CPU / memory / disk space.

CPU is the engine in the computer that does all the work. The memory is a volatile storage area used for programs and work in progress. Disk is the non-volatile storage that holds all your files in an electronic filing cabinet. As an analogy to a Library, think of the CPU as the Librarian, Memory would be the size of the book trolly and disk space would be the size of the shelves and walls of books.

When the computer is new, the resources are mainly free and available to be used by you as and when required. The computer is new, just the basic programs exist and the computer runs quickly and responds quickly to your commands. In our analogy think of this as the council opening a new Library in the high street and you are the only one who has been told about it.

As you load up programs onto the computer and you have the computer work harder for you, doing your email, your accounts and spreadsheets and surfing the internet, your instant messaging and the all important virus checking and backups, so you are putting regular demands on the resources of the computer. Back to our analogy, this is more like a real library where the whole Town knows it exists and the library is continually used for books / magazines / audio and video tapes etc.

There comes a point when the CPU is being worked too hard or the memory is filling up or disk space is running out. This would be where we are asking our librarian to fetch books and stamp books at the same time, or asking for more books than the trolly will carry and even asking for the library to get new books with nowhere to store them.

When this happens you have several choices. You can cut back on the service offered by the library (remove audio / visual books) or limit the number of users of the library thus freeing CPU / Memory / disk apce. You can open another Library in the high street spreading the load across the multiple CPU / Memory / disk space. Upgrade the existing library with a faster librarian or maybe two librarian's, give them a bigger trolly and build an extention to the library.

Large enterprises that I have worked for generally have "Change Management" systems that prevent changes to the computers without prior agreement and notification. When something goes wrong or things slow down on the computer its relatively straight forward to roll-back from the change that caused the problem even if significant periods of time have past. Generally we don't have this kind of control at home and when the computer slow down its normally an exercise in trial and error to determine the cause, but here are some common culprits that slow down our computers:-

Anti-Virus software. Some default installations of this software can slow down computers considerably and un-necessarily, checking every read or every write as well as scheduling complete scans of the disk and memory. Sometimes these AV programs consume significant resources taking away resource from the user until its tasks are complete. In our analogy Anti-Virus could be represented by checking the books are not damaged. Imagine how long it would take if everytime you returned a book the librarian checked that every page was not damaged.

AV plays a significant part in protecting our computers from Malicious software. All computers should have uptodate AV scanning. Make sure that the schedules are set to convenient times like "after 15 minutes of in-activity" and don't choose schedules like "scan upon log in".

MSN live. This can really slow down a computer whilst the computer is starting up and logging in. By default MSN always starts when Windows starts. But this can be changed to only start when its needed.

Online gaming engines such as "Steam" can slow down logon. You may not know what "Steam" is but your kids will if its installed. Steam by default will start when Windows starts but this can be changed to start when required <right-click the steam tray icon><click settings><click interface><uncheck run steam when system starts><click OK>.

Autostart programs, all those little icons down in the right hand corner of the TaskBar or system tray. Everyone of them is eating a small piece of your resources so if you don't need them stop them. Sometimes this is easier said than done (Quicktime is notoriously difficult to get rid of). Try clicking the icons and changing startup options to NOT start when the system starts.

Microsoft provide a tool called "msconfig" that can help manage these "autostart" programs. But be careful playing with this tool as it can render the computer un-startable if you get it wrong.

Memory and CPU. If you right click on the Taskbar you can start a program called task manager. Open the task manager program and select the performance tab along the top, don't type anything for 10 seconds to let the system settle. The program should be displaying a couple of graphs down the left hand side for "CPU History" and "Memory". The CPU history should typically be less than 5% and the memory about 50-60%. If this does not describe your computer then there could be programs running eating into your costly resources. You can use Task manager to identify the culprits and stop the programs.

Its difficult to say how much memory is needed for a PC as it depends on what you are intending to use it for. For reasonable performance, as a rough guide Windows XP should have around 500Mb memory and Windows Vista around 1Gb memory. Both systems will work with less but performance may be impacted. More memory will be beneficial but may not always fix your problems. If you are driving a car with your foot on the brakes, to go faster you could put in a bigger engine OR you could take your foot off the brake.

Disk Space. Open "My computer" or just "Computer" in MS Vista. If you have less than 20% free space you will start to impact performance of the computer. This is due to the algorithms used for determing where and how to store the files and 20% is the magical threshold. Beyond this point the system will slowly find it a struggle to find space quickly and performance will be impacted.

Overtime the files on a disk may become fragment (especially if you are running low on free space). In our Library analogy this would be equivalent to the Encyclopedia Britanica gradually being stored on different shelves due to lack of space. To improve this on our disk drive we can run a "disk defragment" which will shuffle around all the files such that large files are stored contiguously on the disk making read and updates quicker. To use the disk defragmenter select <Start><All programs><Accessories><System Tools><Disk defragmenter>.

Slow Internet Access. Who else is using your network. If one of the kids is using Xbox live or Skype is being used etc this can slow down your internet access. I've also seen some programs implement "parental controls" within one of the internet files "c:\windows\system32\drivers\etc\hosts". If this file is larger than 5Kbytes this may start to slow down internet access..

Unused programs. Computers are like cars and need regular maintenance or housekeeping in order for them to function at their best. If you don't use a program on the computer consider removing it.

This page was Last updated Mar 2009