Well your first priority should be a new RAM but if you can't then try one of these two options.
1. Press Ctrl+Alt+Delete simultaneously, select the processes options and from there close the unnecessary processes.
2. Second option is that click on the Start, write "msconfig" in the run box, from there select startup button and uncheck the programs which you don't want to run in the background while you are working on others.
1. Press Ctrl+Alt+Delete simultaneously, select the processes options and from there close the unnecessary processes.
2. Second option is that click on the Start, write "msconfig" in the run box, from there select startup button and uncheck the programs which you don't want to run in the background while you are working on others.