The issue of how After Effects uses RAM is one of those topics that seems to get asked just about every forum, at least once a week. I’d like to clarify some of the confusion on this.

The fundamental issue revolves around the following issues:

• Despite the amount of RAM one has in their computer, when launching After Effects the splash window (or the About window) will show a much lower amount being used, such as 3GB.
• Furthermore, there is a preferences panel that gives the impression that one has more control over this RAM allocation, and that there is some magic setting to fix the issue.
• That because After Effects only seems to use 3GB of RAM at best, that having between 2-4GB of of RAM is “plenty.”

Cutting to the chase, and to make you a more informed user, I’d like to present the facts, and then explain them in a little detail:

• You SHOULD have more than 4GB of RAM in your computer
• Your computer most likely can and will use more than 4GB of RAM for After Effects

Currently, After Effects on Mac OS X can use up to 3.5 GB of RAM.  After Effects on 32-bit Windows operating systems (XP, Vista 32) can use up to 3 GB of RAM; however, to use more than 2 GB in After Effects, you must configure Windows XP or Windows Vista appropriately.  For details on this, see Jonas Hummelstrand’s website: (www.adobe.com/go/learn_ae_jonaswindows3gb.) After Effects on 64-bit Windows operating systems can use up to 4 GB of RAM with no special configuration.

So, where does the other RAM come in? If you bought 12GB of RAM, was that a waste of money? No!!

When you work with After Effects, knowing full well that it is limited to that RAM that we just spelled out, there’s more going on behind the scenes that you might realize. If you proceed to Preferences>Multiprocessing, you’ll find an option to enable multiprocessor rendering. In fact, you’ll see a very description paragraph as to what multiprocessing actually is doing.

After Effects will “use multiple processes to speed rendering for RAM preview and final output”, ie. rendering.

What are these “multiple processes?”

Behind the scenes, when you render or perform a RAM preview, additional applications launch in the background that you do not see. In fact, the only way to see them is to launch a process viewer. In Mac OS, you can use the Activity Monitor. What you will see are processes called “aeselflink” (AE Self Link.)

These are helper applications that can use up to 2GB of RAM for each CPU. Being that even one “duo core” has 2 CPUs, you can see how this might add up very quickly. A dual quad core computer has 8 CPUs, which can easily eat up as much as 16GB of RAM when rendering. And this doesn’t count any additional programs you might try to run in the background.

If you have a small amount of RAM (less than 4GB), there is a distinct possibility that using multiprocessing will slow down the rendering process. If you lack the RAM for the helper application(s), your computer will use virtual RAM (hard disk space.) This, most likely, will slow the rendering process. This obviously depends on how many CPUs you have, and how much RAM.

So, get that RAM. You SHOULD have a lot of RAM as an After Effects user. For as much as you spent on that computer, having a low amount of RAM will greatly reduce the potential speed of your machine.  This goes for AE CS3 and CS4.