Pardon me, but this is typical RTFM stuff. Your journey starts here:
AE requires RAM previews, it doesn't do realtime in most departments. It's not an editing program!
Wow, is everyone from Adobe so abrasive?
AE has editing capabilities and there's a particular plugin that has necessitated my using it.
I don't understand why the software is so slow, not only to preview, but also to render.
Right now i'm rendering a 30 minute video (320x288) and it says it's going to take 9 hours, yet, I have RAM free, my CPU cores aren't contended, there is no SWAP used and my disk is being hardly hit at all. I have disabled all effects other than some level adjustments.
There's an "After Effects" process at 100% on one core, and 5 aeselflink processes all about 20% and using 2GB of RAM each. I don't get why this thing is so slow at doing something simple that other programs do in realtime.
As Mylenium says, you are thinking about AE all wrong. It is not like Motion; it is much more powerful. That comes at a cost though. The way AE works is not condusive to real-time playback. For proper previewing, you have to create a RAM preview. All that (and much, much more) is covered in the link Mylenium gave you. You must go through some solid training in the basics of AE or you'll just be frustrated.
Make Motion do what AE does and it boggs down too. Motion appears to do things in real time because it's constantly caching in the background. Reach that limit and you're up against slow performance.
AE is also not a program that anyone can use by simply opening it up and dropping a plug-in on some footage. There are so many options for everything that you need to know at least the basics. It's not a NLE, It's not motion. It's a pixel rendering layer based compositing system and it takes time to do those calculations.
I get it, it's a very powerful program, too much perhaps, in the hands of a mere mortal. What I don't understand is why it only using part of my system resources. I've configured it to use 12GB of RAM and 8 cores, but it doesn't max out either and is STILL slow. I don't understand what it is spending time doing.
It's almost like there is a sleep() in the code somewhere. Bizarre.
AE builds a frame at a time. A frame only contains so many bytes. Add in some effects or throw in a particle system and you have more bytes to calculate. Once a frame is calculated then the next one starts. That's why it's very hard to max out all system resources processing a frame at a time. It would take an entirely different rendering system to do more. Until Adobe completely re-writes the way pixels are calculated in AE that's the way it is.
I take all your points on board.
I admit I am a complete outsider and do not know video editing software very well.
I am just making a computer science oberservation video processing should be CPU or GPU bound. When rendering on my macbook pro, the "Adobe QT32 Server" process is single threaded and runs at 100% on one core, and appears to block all the "aeselflink" processes on the other cores - they sit around only using about 25%, presumably because they can't get work-assignments fast enought from teh QT32 server.
Until this blocking is resolved, AE is only partially multi-threaded. I don't know if this is the case for "RAM previews" too, but it's likely if such a big oversight has been made in the core rendering engine.