We need more information.
What exact version number of AE?
What is in your composition? Effects, codecs and format of any footage or assets, number of layers, etc.
Define "slow rate".
And any other info you can think of.
Well, I'm not sure what exact number the version number is, but I always update with the most recent versions. As for my comps, most of my comps are 1920x1080, 29.97 or 24 fps, and i don't use footage much because I usually start from scratch with my effects. I try to use effects like Optical Flares, Sure Target, Trapcode Particular a lot, and I know it takes a lot out of the system to run Particular. I set the emitter size up to maybe 2,000x2,000x5,000 sometimes, because I figure my system will be able to handle it. However, as I'm watching a tutorial and witnessing their RAM preview taking less time to render, it leaves me wondering if there's an issue with my system. By slow, I mean, every time I press '0' it takes 4-6 sec to load one frame, when I feel it should be taking maybe 1 or 2. Also, I watch the Task Manager every time I'm doing something intensive on AE and my CPU always sky rockets to to using 99% of its power. Now is AE a software that uses mainly GPU support, or should it actually be using that much CPU power?
Help>About will show you the version number.
Do you accidentally have the ray-traced renderer turned on for your composition instead of the standard renderer?
Do you have Depth of Field turned on for your camera?
Tutorials often speed up RAM previews to prevent boredom on the part of the viewer.
The size of the emitter is unrelated to the processing power it takes. What matters is how many particles are being created
I watch the Task Manager every time I'm doing something intensive on AE and my CPU always sky rockets to to using 99% of its power. Now is AE a software that uses mainly GPU support, or should it actually be using that much CPU power?
After Effects uses the GPU for very little. See here: GPU (CUDA, OpenGL) features in After Effects
Side note: The ray-traced renderer is now considered obsolete, so if you had not heard about it before, don't get all excited and start learning it. Learn this instead.
CPU and RAM are the two most crucial things for AE. This page might help: Optimizing for performance: Adobe Premiere Pro and After Effects