Reduce Footage Layers is a script from developer jfcg for After Effects, built around non-destructive cleaning of inactive footage layers from your timelines. The focus is on inactive footage layers, handled without a destructive edit to your composition.
As of version 1.24, released May 30, 2025, the script can display a list of unused footage that has been replaced with solids, along with a list of what footage has been removed. Earlier, version 1.23 fixed an issue with the unintentional replacement of offset trackmattes, and the initial 1.22 release shipped in March 2019.
Reduce Footage Layers is compatible with After Effects 2025, 2024, 2023, 2022, 2021, and 2020, plus the CC 2019, CC 2018, and CC 2017 releases. A demo video is available, and the developer's aescripts page carries the full changelog and current details.