We need to know a lot more to help you. Please provide answers to the questions listed here: "FAQ: What information should I provide when asking a question on this forum?"
Also, tell us exactly how you're determining how much RAM After Effects is using.
Consider that not all operations will use the same amount of RAM; sometimes, the limiting factor is CPU, GPU, or disk/bus speed. It depends on the composition, output settings, and more.
Details of memory usage in After Effects are here:
WhIle rendering in AE, the amount of RAM being used is indicated at the bottom of the program, so that informtaion comes directy from AE. I do not run any background programs while rendering because I know this will slow down the render time. The source footage is an mp4 video tutorial that I record using Camtasia, which is usually 10 minutes long. I import the footage into AE and add a Lower Third. I've always used the same Lower Third and I don't add anyting else. While redering the video, including the Lower Third, the memory usage has always been at 80% prior to today. I haven't installed anything new on my computer prior to this happening. I'm using CS6 on Windows 7.
Hello, can you please provide a screen shot or two showcasing your issue and key settings on your computer?
It's much easier to do delicate surgery with the light on.