How to Allocate CPU Cores in After Effects

Adobe After Effects handles processor utilization dynamically through Multi-Frame Rendering (MFR), scaling active CPU cores based on hardware capacity rather than a manual core-count toggle. This guide explains how to enable Multi-Frame Rendering, adjust CPU and RAM allocation settings to maximize core usage, and apply system-level limits if you need to restrict core usage during export.

1. Enable Multi-Frame Rendering

To utilize multiple CPU cores for previews and final exports, ensure that Multi-Frame Rendering is active:

  1. Open Adobe After Effects.
  2. Navigate to Edit > Preferences > Memory & Performance (Windows) or After Effects > Settings/Preferences > Memory & Performance (macOS).
  3. Under the Performance section, check the box labeled Enable Multi-Frame Rendering.

2. Configure CPU Reservation

After Effects allows you to control the percentage of your processor dedicated to rendering versus background system tasks:

  1. In the Memory & Performance preference window, locate the % of CPU reserved for other applications setting.
  2. Adjust the percentage slider:
    • Lower percentage (e.g., 10%): Allocates the maximum number of CPU cores to After Effects, resulting in faster render times at the cost of system responsiveness.
    • Higher percentage (e.g., 30%–40%): Restricts the number of cores After Effects can saturate, keeping your system responsive for multitasking or running other software simultaneously.
  3. Click OK to apply the changes.

3. Balance RAM Allocation to Unlock Cores

Multi-Frame Rendering calculates active core count based on your total system memory. Each core requires a minimum block of RAM (typically 2 to 4 GB per core) to process a frame concurrently. If memory is insufficient, After Effects will automatically throttle the number of cores it deploys.

  1. In the Memory & Performance menu, review RAM reserved for other applications.
  2. Lower this value to the minimum recommended threshold to free up the maximum amount of RAM for After Effects.
  3. Increasing available memory directly allows the MFR engine to engage additional CPU cores during rendering.

4. Manually Restrict Cores via Operating System

If you need absolute control over specific CPU cores allocated to After Effects, manage core affinity directly through your operating system:

  • Windows: Open Task Manager, go to the Details tab, right-click AfterFX.exe, select Set Affinity, and manually check or uncheck specific processor cores.
  • macOS: Use the terminal utility taskpolicy or third-party process management utilities to bind specific threads or throttle CPU limits for the After Effects process.