Un-install unused programs: To remove these click "Start" then go to "Control Panel" then click "Programs and Features" and scroll through the list, uninstalling the ones you never use.
Delete Temporary Files: To get rid of all this clutter open "My Computer", select your main drive, click the "Windows" folder then open the folder inside that called "Temp". Use your mouse to right-click on the folder, and in the "View" options, choose "Details". Once this is done, select all the files that are older than the current date and press the delete key. Then go to the Recycle Bin on your desktop and empty it.
Stop un-necessary Start ups: Whenever you switch on your PC some programs will automatically start to run in the background which will use your computer's memory and make it slow . To disable these programs click Start and type "Run". In the box that appears type "msconfig" and a box will appear, at the top click the "Startup" tab listing all the applications that run when your computer starts up. Either manually untick the ones that are unnecessary or click "disable all", but be sure to keep vital things like antivirus going.
Get more RAM: When you try to work on several applications at once, such as email, internet, and word your computer may slow down . This is because you don't have enough RAM. This is memory used by your PC to run the programs and can be easily upgraded
Get your software up to date: Using older versions of a browser can seriously slow things down – especially if you’re looking at pages with lots of pictures or watching videos Upgrading to the latest version of the browser you use , like – Google Chrome, Mozilla Firefox, Safari or Internet Explorer - may really speed things up
Upgrade to a faster Network Adaptor: Your device’s network adapter should comply with the latest 802.11ac WiFi standard. Any network adapter that uses an older protocol (802.11n, 802.11a, 802.11b, or 802.11g) is not able to take advantage of very high speeds