Frustrated by AE--I obviously don't know what I'm doing...

Thank you both for your reply, looks like I was doing more right than I thought...I do most of the things you mention and will do the ones like turn off motion blur. However, I have two empty memory slots and I think my next step is to fill them...From what I can tell that is around a $600 purchase. I may be able to save money by installing myself...that it is if I don't screw it up...

Here are my mac specs:

Here is the animation I have been working on that was giving me trouble: https://youtu.be/JedMY_uHdZM As you say, it's easier to just render sometimes...

I sincerely appreciate all the good information you shared with me Rick, very helpful.

Niki

As Rick said already, without any idea about your project contents, preview settings, your system and so on we can't really tell you much. Most of these slowdowns hinge on problems with hardware accelerated rendering and UI functions, so this would have to be your first stop. Check the relevant settings, update your system's graphics driver if possible. For anything beyond that, indeed much more info will be required.

Mylenium

Playback duration and Ram Preview render time depend entirely on your composition frame size and frame rate, the composition panel settings, the Preview panel settings, your available system resources, your system specifications, and even the read/write speed of your disks. 

The typical workflow an AE pro uses is to set the Composition Panel resolution to Auto, set the Magnification ratio to Fit or 50% or less, turn off motion blur and any unnecessary effects, and then render a Ram Preview to check the timing and position of the animation. If needed, the Preview Panel can be set to skip frames. In honor of the history of animation, I call this a Pencil Test. 

When the timing, blocking, and composition are where you want them to be, it is time to turn on Motion Blur, all effects, set the Magnification Ratio to 100%, and check a few of the hero or critical frames to make sure that everything is as it should be. On most systems, this means you might not even be able to see the entire comp at one time. I call this step Ink and Paint. When the final quality of the most critical frames is the way I want it, I send the comp to be rendered. Most of the time I will ram preview a couple of seconds of the comp at critical points in the timeline, but I never expect to be able to run a full resolution preview on every comp. Every system is different. When I first started using After Effects, we had to render everything because there was no such thing as a Ram preview. Now, depending on the machine I am using and the design of the comp, I can get ram previews for most of my VFX work that lasts 10 or 15 seconds on my fastest machine, but the same comp will only ram preview 2 or 3 seconds on my slowest machine. Any effect you add to your composition will slow down the render time. Some effects take so long to render that the best option you have for preview is to render the comp using the Render Queue.

The only way to really judge a comp that is longer than a few seconds is to render the comp and check it at 100% so you can see every pixel in real-time. If you want us to give you an estimate of the ram preview render time for your comp we need workflow, project, OS, and system details.