Live preview plays your arranged clips back in real time directly in the browser so you can judge pacing before committing to a render. Because it's live and local, its smoothness depends on your device's available processing power at that moment, not on the eventual quality of your export.
Likely cause: too much happening in the tab at once
Stutter is most common with long sequences, high-resolution source clips, or a project with many clips loaded, especially when combined with other demanding tabs or apps running at the same time. The browser is doing real-time decode and compositing work, and that has limits on any given device.
Other contributing factors
| Situation | Effect on preview |
|---|---|
| Many other browser tabs open | Competes for CPU and memory, making stutter more likely |
| Very high-resolution source clips (e.g. 4K) | More data to decode per frame during live playback |
| Long edit plan with many scene changes | More frequent clip transitions to render on the fly |
| Older or lower-powered laptop | Less headroom overall for real-time playback |
Ways to smooth it out
- Close other tabs and background apps before reviewing a preview closely.
- Preview shorter sections of your plan at a time rather than the full 90 seconds in one continuous play.
- Give the tab a moment to catch up if you've just scrubbed to a new position, rather than judging pacing from the first stuttering second.
- Restart the browser tab if performance degrades noticeably over a long editing session.
Rendering uses FFmpeg to process the final file frame by frame rather than playing it back live, so a choppy preview does not translate into a choppy exported MP4.
When to stop troubleshooting and just export
If you've confirmed your clip order and trims are correct and the stutter is purely a live-playback performance issue, you don't need to chase it further before rendering — export and check the actual output file instead of continuing to fight the preview.
When it's worth investigating further
If the stutter is severe enough that you genuinely can't judge pacing or catch obvious cuts, that's worth resolving before you export, since a preview you can't trust makes it harder to decide between multiple generated edit plans.
Does closing and reopening the project help?
Sometimes — it clears any accumulated browser state from a long session, similar to a tab refresh.
Should I use a lower export resolution to fix preview stutter?
No, export resolution and preview performance are separate; changing your export setting won't change how the live preview plays back.