EC2 Instance is running very slow

I am running an EC2 Instance on Ubuntu Server machine. Tomcat and MySQL are installed and deployed java web-application on it since 1 month. It was running good with great performance for almost 1 month but now my application is responding very slow. Also, point to note is: Earlier when I used to log into my Ubuntu Server through PuTTY, it was quick but now its taking time even when I enter Ubuntu password.

Is there any solution?