Showing unmounted componentsv4.0.536

By design, Remotion renders only the current frame.
This keeps previews fast even when a video is long.

In the Remotion Studio, Remotion also evaluates components outside their active time range to better visualize the timeline:

Items that are not visible at the current frame can still be shown.
The timeline stays stable as you scroll and seek through the video and doesn't jump.

This discovery only runs in Studio, if you use React 19.2 or later.

Keeping discovery fast

Remotion reduces the cost of evaluating these components:

Actual content such as videos and audio is disabled where possible and only metadata is being registered.
Components are wrapped in React's <Activity> with mode="hidden", which keeps their content invisible in the DOM.
React Effects do not run while the components are hidden inside <Activity>.
The components' frame stays fixed during discovery, avoiding updates on every playback frame.

Your component's render function still runs.
Expensive calculations during rendering can therefore slow down discovery.

Open Settings → Studio → Timeline and change "Visualize unmounted components".
The default is unlimited discovery.

Set a lower number if discovering all components makes a large composition slow.
Remotion prioritizes components closest to the current time.

You can also set the limit in your config file:

remotion.config.ts
import {Config} from '@remotion/cli/config';
Config.setSequenceActivityLimit(20);

Terminal
bunx remotion studio --sequence-activity-limit=20

Set "Visualize unmounted components" to 0 in Settings → Studio → Timeline.

To disable discovery in your config file:

remotion.config.ts
import {Config} from '@remotion/cli/config';
Config.setSequenceActivityLimit(0);

Or pass the CLI flag:

Terminal
bunx remotion studio --sequence-activity-limit=0