No matter how expensive car you buy, it need to be serviced. Same applies to your PC. With usage, the problem of computer running slow is normal unless it is properly maintained and serviced. Having internet connections, downloading loads of stuff, installing & using different applications take a toll on your computer, thus making it slow.
Some of the common reasons for computer running slow are:
1. Not enough RAM: RAM stores your temporary files. If there is no enough RAM i.e less than 512MB then consider adding more. At-least 1GB is preferred for better speed.
2. Unnecessary & uncontrolled application running: Many programs when installed will install a quick launch feature, that allows them open during start-up. These programs keep running till you shut down your system. Look at the right corner of your windows tool bar to find the programs running. Close all unnecessary files. You can also check your windows task manager to find unnecessary running files and end them. There also softwares which list the Startup softwares and allow you to turn off the one not needed.
3. Lack of maintenance: Many computers are filled with lots of unnecessary files, mainly in C drive. All the outdated software, unused game softwares, Zip files of softwares downloaded, deleted files in recycle bin etc. Either delete all these or save them in an external drive or in some CD. Remember to keep at least 10% of your software storage drive- normally C drive- free. Can use Windows disc cleanup to delete temporary files. If you’re an expert then you can use Windows registry.
4. Malwares & Spywares: In most cases these are the greatest contributor for slow computers. Using updated versions Anti-Malwares and Anti-spywares in safe mode will help to restore your computer to normal mode. Usage of two or three such applications will provide higher security.
5. Fragmented Hard drives: Windows tend to scatter files all around free space. This causes slower file searches. De-fragmentation leads to assembling file segments resulting in easy file searches.
start > all programs > Accessories > system tools > disk defragmenter.
select the disk you need to defragment, mainly C.
6. Overheating: Again one of the major cause for Computer running slow. Open the case and clean the dust collected on the fan and ensure no obstruction for air circulation. Usage of computer in Air Conditioned room adds to the advantage.
All these known, check that whether the system requirements of the softwares installed is matching or not, Mainly if you are using an old computer. Or else even that may be reason. At last, to keep your computer in good form, maintain it.