You can improve performance by optimizing your computer system, After Effects, your project, and your workflow. Some of the suggestions here improve performance not by increasing rendering speed but by decreasing time that other operations require, such as opening a project.
By far, the best way to improve performance overall is to plan ahead, run early tests of your workflow and output pipeline, and confirm that what you are delivering is what your client actually wants and expects. (See Planning your work.)
Lloyd Alvarez provides the BG Renderer script on the After Effects Scripts website, which allows you to render and export compositions in the background while you continue to work in After Effects.
Todd Kopriva provides more information about optimum memory and processor settings on the Adobe website.
See Memory preferences for additional information.
Import projects from After Effects CS5.5 and earlier into After Effects to take advantage of the Global Performance Cache. For details, see Disk Cache.
Persistent disk cache improves performance by retaining frames stored in the disk cache between sessions, saving rendering time as you work on a project or other projects that might use the same cached frames.
By simplifying and dividing your project, you can prevent After Effects from using memory and other resources to process elements that you are not currently working with. Also, by controlling when After Effects performs certain processing, you can greatly improve overall performance. For example, you can avoid repeating an action that needs to happen only once, or you can postpone an action until it is more convenient for you.
You can improve performance in many ways that don’t affect how After Effects treats your project data, only how output is drawn to the screen as you work. Although it is often useful to see certain items and information as you work, After Effects uses memory and processor resources to update this information, so be selective in what you choose to display as you work. You will likely need to see different aspects of your project at different points in your workflow, so you may apply the following suggestions in various combinations at various stages.
Pressing Caps Lock suspends updates (disables refresh) of previews in viewers during rendering for final output, too, although no red reminder bar appears.
Some effects, such as blurs and distortions, require large amounts of memory and processor resources. By being selective about when and how you apply these effects, you can greatly improve overall performance.