1. Stop all unused applications. The Task bar is on the bottom edge of the screen (unless relocated by the user). In the right side of the Task Bar appears a group of small icons, collectively named as the "system tray". Each of these icons represent a program that has been at least partially started or is running "in the background". Regardless of state, each causes a reduction of available memory and processing power, or resources. Closing, exiting or canceling any unused icon returns those resources to the system, and becomes available for use by the application(s) started specifically by the user. Go to your task manager and click on the Process tab. End all process that you can.
A utility called Process Explorer (procexp.exe) can be used to list all programs running on your Windows system. It is more comprehensive than the Task Manager, and hovering your mouse pointer over any program name will tell you what it is about.
A utility is built into Windows that can enable/disable task bar programs and processes from automatically loading with Windows. To access it, go to Start > Run > type in “MSCONFIG” and click OK. If you do not know what a process does, search its name. Do not disable processes if you are unsure, as some processes are necessary for your computer to function normally.
A useful freeware program called Game Booster by IObit (the same people who wrote the well regarded Advanced SystemCare software) will temporarily disable unnecessary background processes and boost performance on your computer when you are actively using only one program; such as a game program or video editing software. When you are finished, you can resume "normal mode" and all the background processes will be reloaded.
Follow here for tip 2-
http://answers.techzim.co.zw/11280/is-your-computer-slow-tips-to-speeding-it-up-2-13
Follow here for tip 3-
http://answers.techzim.co.zw/11281/is-your-computer-slow-tips-to-speeding-it-up-3-13