In After Effects CC 2015 (13.5), some features that were available in previous versions of After Effects have been removed or disabled. All these features are related to rendering or previewing frames. The interactive performance improvements in After Effects CC 2015 (13.5) required rearchitecture of the code for how frames are rendered and then returned for processing (that is, previews or exporting).
Sometimes, a feature has been disabled temporarily because it is being rewritten for the new After Effects architecture, and that work is not yet complete. Adobe intends to re-enable some of these features in a future update to After Effects. In other cases, the feature has been removed permanently.
If you still want to use these features with your project, open project files saved by After Effects CC 2015 (13.5) in After Effects CC 2014 (13.2). Project files are directly compatible between these versions; you do not need to save back a version. Both versions of After Effects can be installed on the same computer at the same time.
The After Effects team understands that the removal of features can be disruptive. Adobe would appreciate you telling us on the After Effects forum which of these features is most important for you (and why). That way, Adobe can best prioritize the rewriting or replacement of these features.
The following features have been removed or disabled in After Effects CC 2015 (13.5):
Render Multiple Frames Simultaneously (Multiprocessing)
The Render Multiple Frames Simultaneously feature was superseded by the new architecture in After Effects CC 2015 (13.5). The new architecture will allow a future version of After Effects to use processor threads and RAM more efficiently than the Render Multiple Frames Simultaneously functionality.
Options related to Render Multiple Frames Simultaneously have been removed from the preferences, and Preferences > Memory & Multiprocessing has been renamed to Preferences > Memory.
If you want to use Render Multiple Frames Simultaneously to speed up final rendering via the render queue, you can still do so by opening the project in After Effects CC 2014 (13.2).
Cache Work Area in Background
The Composition > Cache Work Area in Background command has been removed. It depended on the now-removed Render Multiple Frames Simultaneously functionality. Similar functionality using the new architecture could be implemented in the future.
Brainstorm has been removed.
Watch Folder rendering
Choosing File > Watch Folder in After Effects CC 2015 (13.5) displays a dialog with a link to this page.
Watch Folder rendering requires additional work to the new architecture.
You can use Watch Folder rendering in After Effects CC 2014 (13.2) with projects saved by After Effects CC 2015 (13.5).
Render Queue previews
After Effects CC 2015 (13.5) does not display a preview of compositions being rendered via the render queue. For the new architecture, the code for both the render queue and previewing compositions was substantially rewritten, and this functionality requires additional work.
The related option in Preferences > Video Preview, Video Preview During Render Queue Output, has been disabled.
Adobe plans to reimplement this functionality in an update to After Effects CC 2015 (13.5).
Progress indicators on the After Effects icon in the Mac OS dock during previews and render queue rendering
The icon for After Effects CC 2015 (13.5) in the Mac OS dock does not display a progress bar, frame count, or render item count while previewing or render queue rendering. This functionality requires additional work to the new architecture.
Save Current Preview (formerly Save RAM Preview)
The Composition > Save Current Preview command is disabled. It requires additional work to the new architecture. Adobe plans to reimplement this functionality in an update to After Effects CC 2015 (13.5).
This command was previously named Save RAM Preview. It was renamed due to the removal of the term “RAM Preview."
Alternate RAM Preview
The Alternate RAM Preview functionality and its options in Preferences > Previews have been removed. Improved functionality using the new architecture could be implemented in the future.
Ping Pong loop
The Loop button in the Preview panel can no longer be set to Ping Pong mode. This functionality requires additional work to the new architecture.
Hardware Accelerate Composition, Layer, and Footage Panels
The Hardware Accelerate Composition, Layer, and Footage Panels option in Preferences > Previews is disabled. It requires additional work to the new architecture.