How to reduce ram usage after Windows 8.1 update

Somehow it looks like Windows 8.1 is not really working well after a upgrade. I had directly upgrade my system from Windows 7. I am having in total 4GB ram on the system. And the performance here is not upto the mark. When the pc turned off and done with configuration of all settings, it takes too long time to respond. The ram usage is very high. It is taking around 3GB of ram all the time. And when I turn on movie maker again it slows down. I want to reduce this so that other applications can also work well. How to do that. I am clueless about the issues.