How To Determine Why Your Computer Is Running Slow
By Ryan Williams, TechBetter.com - This question was submitted by a reader in New Jersey. The reader wants to know how to determine why her computer is running slowly. Thank you for the question. This is a relatively easy thing to do and should help a lot of people.
NOTE: This tech tips uses Windows Vista as an example, however the process is nearly the same in Windows XP.
To check which programs are currently running on your computer, right click on your task bar where no icons or tasks are located.
Example: http://www.techbetter.com/ttimage.aspx?image=runningtasks01.gif 
On the context menu that appears after you right-click, select 'Task Manager'.
Example: http://www.techbetter.com/ttimage.aspx?image=runningtasks02.gif 
The Task Manager window that appears next will show you every program running on your computer. You can sort these programs by name, by CPU utilization and by memory usage by clicking on the corresponding column headers. I usually sort by CPU utilization percentage when I am troubleshooting why a computer is running slow. The higher the percentage the more CPU the program is hogging to itself. Be sure to click the column header twice to sort the column from highest to lowest so that the programs taking the most resources appear at the top of the list.
Example: http://www.techbetter.com/ttimage.aspx?image=runningtasks03.gif 
This is useful because often times when your computer is running slow it is because one or more programs are stealing all of your CPU and starving the rest of the programs on your computer. Examples of when this can occur include when an antivirus program is running a full system scan or when an automated backup routine is backing up your files.
Viewing your tasks in Task Manager will show you which programs are hoarding your computer resources, but what if you don't know what the running programs are for or if they are actually necessary? This is where the website ProcessLibrary.com comes in handy. You can enter the file name of the running program on your computer and ProcessLibrary will tell you if the file is safe and what the program is actually used for. In the following example, I looked up the program dwm.exe which is running on my computer. The website tells me that the program was developed by Microsoft and that the program is safe. If the program was spyware or something similar the site would alert me to remove the file.
Example: http://www.techbetter.com/ttimage.aspx?image=runningtasks04.gif 
Using this method it is easy to determine which programs are causing your computer to run slow AND if those programs are legitimate or need to be removed.
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