1. close all the applications running in the background, you can see them in the right lower corner of you screen on the task bar. Just right click and quit them.
2. type "run" (without double inverted comma) in search box in start and open the run app. In that type "msconfig" (without double inverted comma) and a window will pop up then go to "startup" tab, and you will see few app which are ticked in the box to the left.
3. Just untick all those apps expect your ativirus and apply and then click ok.
4. After you restart your computer only antivirus will be running and you ram usage will be like 20% which is great.