how to improve computer speed

most question about computer speed are as follows...
1-how to increase internet speed
2-speed up my pc
3-speed up my computer
most problum of now a day is reduced speed of computers.
there are many ways to increase the computer speed.
First of all you have to check your RAM and PROCESSOR combination
if there combination is strong then restart your computer or
reinstall your window and after installing your window first of all you have to install anti virus to protect your computer.