how to fix slow working problem of pc

Computer lagging

computer lags when a lots of application running in background. there is easiest way to kill all unnecessary tasks. after killing unnecessary tasks, The computer stops lagging. there  are some steps
given below. use these steps and if your computer lagging then it will stop lagging.

step 1 : right click on  task bar.
step2 : click  on task manager.
step 3 : go to process tab.
step 4 : zoom out the description box.
step 5 : look at the software name in description tab and end task
step 6: kill all task by using step 5.
step 7 : close the task manager.