Upcoming Boost to After Effects Preview Playback with RAM and Disk Cache

Introduction

Last month, the Adobe After Effects team announced an upcoming modification that improves Preview playback performance by changing how cache is processed and utilized. This update, which Adobe called “Improved Caching for Longer Playback” in the blog post linked above, but now refers to as “High-Performance Preview Playback” (HPPP), is currently available in AE Beta version 25.2 and can be enabled in Preferences under the function “Preview from Disk Cache”. HPPP improves Preview playback performance by utilizing disk cache for longer playback, relying less on RAM (memory) to solely store and playback frames in a composition.

Before version 25.2, users needed a significant amount of RAM for long and complex compositions, as exhausting available memory would limit preview duration. With HPPP, cached frames stream directly from disk into RAM in real-time, extending playback duration beyond RAM limitations for long and complex compositions.

After Effects renders individual frames and temporarily stores them as cache in RAM. When memory is insufficient, fewer frames can be stored, and when RAM is exhausted, After Effects stops caching new frames, forcing it to overwrite previously cached frames when scrubbing through a composition. As a result, RAM capacity directly affects the complexity, length, and duration of Preview playback, limiting how much of a composition can be cached at once.

Preview Playback in Version 25.1

Disk cache, on the other hand, stores frames more permanently on a designated storage device, such as an internal NVMe drive. This allows users to reopen a project and retain previously rendered frames without the need to re-render. After Effects utilizes both RAM and disk cache to store rendered frames for playback, each affecting Preview and playback performance differently. 

Cache stored in RAM enables instant frame retrieval for smooth playback and scrubbing but is limited in capacity. While a storage drive used for disk cache provides significantly larger capacities than RAM, its performance depends on the raw read and write speeds of the drive, which is inherently slower than retrieving frames directly from RAM.

High-Performance Preview Playback (HPPP) in Beta Version 25.2

The High-Performance Preview Playback modification optimizes how After Effects handles cache, allowing it to continuously load frames into RAM for ongoing playback. By streaming frames from disk to RAM in real-time, After Effects preloads cached frames with a read-ahead function, improving playback and reducing delays from storage bandwidth limitations. This continuous cycle between disk and RAM creates a steady flow of cached frames, keeping Preview playback smooth and responsive, even in longer or more complex compositions.

Since After Effects does not drop frames during playback, every frame remains in cache as long as memory allows. With HPPP, when RAM is exhausted, After Effects no longer stops caching frames and loading to memory, instead it streams cached frames from disk into RAM, allowing playback to continue uninterrupted. As a result, large amounts of RAM may be less critical for caching and Preview playback, shifting the focus toward balancing RAM capacity with disk storage performance for optimizing playback of longer and complex compositions.

Testing HPPP

This blog post focuses on how the modification to RAM Preview functions in real-world use and whether Adobe’s claim that it improves performance on lower-spec systems holds true. More specifically, we examine how efficiently the High-Performance Preview Playback modification cycles cache between disk and RAM during playback and whether it reduces the need for large amounts of RAM for After Effects systems.

To understand the impact of HPPP, we compare After Effects version 25.1, the latest public release, with Beta version 25.2. Using visual comparisons, we analyze how After Effects utilizes disk cache during playback.

For testing, we used our Puget Bench After Effects benchmark composition, “Pulse,” a slightly modified version of Adobe’s Multi-Frame Rendering project from a few years ago. The composition runs at 1920×1080 resolution, 8 BPC bit depth, and 24 FPS, totaling 413 frames or ~17.21 seconds in duration. We are specifically analyzing the composition cache, which stores frames at the composition level for playback, as it directly affects Preview performance and playback efficiency.

Before moving forward, we want to clarify that this is not a hardware performance comparison to evaluate how HPPP performs across different system configurations. Instead, this exploration focuses on how HPPP differs in general functionality from RAM Preview in version 25.1, as this may determine whether we need to update our recommended After Effects systems.

While this update primarily impacts Preview and playback performance, rendering performance depends on system hardware, which we will not cover in this post. However, if you want to see how different components impact After Effects performance, check out our hardware recommendations page.

How Well Does HPPP Work?

Because we didn’t want to have to play through long compositions to hit our RAM limitations, we artificially limited After Effects’ memory usage to 2GB on a system with 64GB of RAM (2x32GB 5600MHz) while testing RAM Preview in After Effects 25.1 and Beta version 25.2. We examined how many frames Preview loads and plays back at different memory limits while also measuring how efficiently it streams disk cache to RAM.

In version 25.1, RAM stops loading cache as soon as it reaches capacity. However, in Beta 25.2, HPPP continues the process by streaming disk cache into RAM, allowing playback to proceed without interruption.

The log files reveal that in version 25.1, After Effects rendered only 46 frames — just 11% of the total composition — before stopping due to RAM exhaustion. In contrast, Beta version 25.2 rendered all 413 frames, continuously recycling RAM to render new frames while streaming from disk cache when memory reached capacity. Even under extremely limited memory, After Effects 25.2 was able to render, cache, and stream the entire composition without noticeable latency during playback.

After confirming that enabling Preview from Disk Cache allows After Effects to play back compositions with as little as 2GB of RAM, we wanted to see how this feature performs when utilizing the maximum available memory. To test this, we increased RAM usage to 58GB and observed how After Effects handles caching and playback when more memory is available.

Performance Comparison Video at 58GB of RAM

With more RAM, After Effects stores more cached frames, reducing reliance on disk cache for continuous streaming. In other words, After Effects can load a greater number of frames into memory, decreasing the need to retrieve them from disk. 

However, the trade-off depends on composition duration and complexity. More complex frames generate larger cache files, which take up more memory and shorten the total duration that can be stored in RAM. In contrast, a longer but less complex timeline can maintain a greater duration in memory before requiring disk cache retrieval. When working with highly detailed compositions, each frame demands more RAM, limiting the total number of frames that can be cached and increasing the frequency that After Effects streams from disk cache to RAM. 

Mathematical Limitations

With HPPP lowering the barrier to entry for users with less RAM, the question becomes: when is more RAM still necessary? To better understand this, we need to examine how disk cache and RAM interact under different composition settings.

Fortunately, RAM and storage usage in After Effects can be directly calculated. Below, we outline mathematical equations that break down the theoretical performance limits of disk drives and RAM.

To determine the capacity to store uncompressed frames at full resolution on your storage drive, you can use this mathematical formula:

Side note: Preview Scale is intended to let you compensate for using lower-resolution previews if you so desire. For full resolution (default) keep this value at 1, but for half-res set it to 0.5, for quarter-res use 0.25, etc.

To determine how much GB of RAM you’ll ideally want based on the length and FPS of your composition, you can use the formula:

Based on our Pulse composition, the table below outlines the theoretical minimum storage and RAM requirements needed to render, cache, and play back frames in Preview successfully.

Height	1920
Width	1080
Preview Scale	1
BPC	8
/ 2,097,152	2,097,152
Megabytes (MB)	7.91015625
FPS	24
MB/s	189.84375
Total Playback (frames)	413
MB Total	3,266.894531
GB Total	~ 3.27

Seconds of Playback	17.21
FPS	24
Height	1920
Width	1080
BPC	8
/ 2,147,483,648	2,147,483,648
+3	3
GB Total	~ 6.20

Our calculations show that for storage, each frame accounts for roughly 7.91MB. Multiplying this by the frame rate (24 FPS) results in a data transfer rate of 189.84 MB/s, indicating the minimum read/write speed required for smooth playback. To estimate the total cache size, we multiply the per-frame size (7.91MB) by the total number of frames (413), yielding approximately 3.27GB of data for this composition. To verify, users can check the disk cache folder and compare the actual cache size with these estimates. Additionally, at least 6.2GB of RAM is required to load all cached frames from the composition into RAM for Preview playback.

Now, let’s consider a scenario where a user wants to push the limits of HPPP by working with an 8K composition, 16-bit depth, 24 FPS, and a total duration of 20 seconds. 

Height	7680
Width	4320
Preview Scale	1
BPC	16
/ 2,097,152	2,097,152
megabytes (MB)	253.125
FPS	24
MB/s	6,075
Total Playback (frames)	480
MB Total	121,500
GB Total	121.5

Seconds of Playback	20
FPS	24
Height	7680
Width	4320
BPC	16
/ 2,147,483,648	2,147,483,648
+3	3
GB Total	~ 121.65

Based on these calculations, an 8K, 24FPS, 16-bit depth composition with a 20-second duration requires 121.5 GB of storage for cache and at least 121.65GB of RAM to load cached frames for smooth Preview playback purely from memory. The increase in resolution and bit depth results in larger frame sizes, demanding a lot more storage capacity than 1080P or 4K content.

If you were working on a composition like this without that much system RAM available, in the past After Effects would struggle and be unable to preview the entire duration smoothly. Soon, in AE 25.2, enabling Disk Cache from Preview (HPPP) could instead take over and provide smoother playback!

However, there is a caveat: to prevent throttling and playback latency, the drive where your cache is stored must be able to read and write fast enough. In the example above, sustaining the transfer of cache from the disk to RAM would require using a drive with sequential read speeds in excess of 6,075 MB/s. That is right on the edge of what is possible with current PCIe Gen 4 NVMe drives and may actually be too fast for long-term usage due to thermal throttling. This shows that some larger compositions may still perform best on workstations with high memory capacity – and this may also be a workload where higher-speed Gen 5 SSDs could provide a tangible benefit.

To summarize: as composition complexity increases, RAM requirements scale accordingly to efficiently load and manage cached frames. For HPPP to function seamlessly, the storage drive must handle high-speed read/write operations, while sufficient RAM minimizes reliance on disk cache streaming. A higher RAM capacity allows After Effects to store more frames in memory, reducing the need for frequent disk cache access and improving overall playback performance.

What Does This Mean For After Effects Workstations?

With High Performance Preview Playback fundamentally changing how After Effects utilizes RAM and disk cache, users will need to rethink system requirements. Once version 25.2 is officially released, most existing hardware recommendations for After Effects will be outdated.

HPPP has the biggest impact on users with limited RAM, particularly those on laptops and mobile workstations, where RAM capacity is often restricted. By shifting more of the caching process to disk, HPPP allows users such as illustrators, motion designers, and 3D artists to work without being limited by memory constraints. This change makes portable and budget-conscious systems more viable for After Effects workflows. 

For high-RAM workstations, the impact of HPPP may be less noticeable. Systems with ample memory can store more cached frames in RAM, reducing the need to access disk cache as often. So, does this update eliminate the need for large amounts of RAM? Not entirely. As higher-resolution workflows become more common, additional RAM may still be necessary if the required bandwidth for the disk exceeds what is possible with a typical workstation configuration. 

Once users upgrade to version 25.2 of After Effects, we suspect that those looking for a new workstation will opt to “pull back” the amount of RAM in the system by a little bit, depending on budget, and invest those cost savings into a larger, dedicated NVMe cache drive. For example, instead of getting 128GB of RAM and a 1TB cache drive, instead, go with 96GB of RAM and a 4TB drive. But, of course, every workflow is different, and we highly encourage you to get in touch with one of our consultants if you are in the market for a new After Effects workstation.

With disk cache now playing a larger role in playback performance, the capacity and performance capabilities of storage drives are more important than ever. Read/write speed, reliability, and lifespan determine how well After Effects streams cached frames, and frequent disk activity can impact long-term drive performance. In short, a well-balanced system with sufficient RAM and high-speed, reliable storage ensures seamless playback, reducing potential bottlenecks in playing back frames in a long and complex composition. 

We plan to explore the maximum limitations of HPPP in future testing, including how it scales with higher resolutions, bit depths, frame rates, longer durations, and storage endurance. This involves evaluating storage capabilities, RAM capacities, and disk cache performance in complex compositions. We hope to determine where performance bottlenecks arise and what system configurations we recommend to best support After Effects workflows once version 25.2 is released to the public. 

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