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Preview Render Files in Filmora (Windows)

The Preview Render Files feature in Filmora helps smooth timeline playback when a project includes high-resolution footage, multiple effects, transitions, or other demanding edits. Instead of struggling to play every change in real time, Filmora creates temporary preview files for the edited sections. This can reduce lag and stuttering while you review your work.

Filmora provides both Manual Render and Background Render options. Background Render can automatically process the timeline after a set period of inactivity. Once a section has rendered, the indicator changes from red to green; editing that section again usually requires a new render.

Manual Render (Render Preview)

Step 1. Identify Sections That Need Rendering

Look above your timeline tracks for a Red line, which shows parts of your video that need rendering.

Step 2. Start Render Preview

Go to File, click Render Preview, and wait for the progress box to finish rendering your files.

Step 3. Check the Render Status

Watch the red line turn Green, which means your video is ready for smooth playback without lag.

Note:

You will need to wait until the rendering process is finished to continue editing.

Auto-Render (Background Render)

Step 1. Open Performance Preferences

Open File > Preferences > Performance in Filmora.

Step 2. Enable Background Render

Find the Background Render option in the Performance tab, enable it, and click Apply.

Note:

The rendered parts of your timeline will be indicated by a green line. The line will be red for the un-rendered parts. Once you change, modify, or add effects to the rendered section you'll notice the line turning red to indicate you need to render again.