Stop the FCP Madness: 5 Annoying Things and Their Easy Fixes

There are a handful of FCP behaviours that look like bugs until you understand why they're happening. Here are five of the most common frustrations and exactly how to fix each one.

01Playback is laggy even on a powerful machine

The most common culprit is background rendering. When it's on, FCP constantly writes render files to your library in the background, consuming disk write bandwidth and CPU cycles at the same time as you're trying to edit. Go to Cmd+Comma → Playback and turn off Background Render. The difference in responsiveness is often dramatic. Render manually when you need it with Ctrl+Shift+R.

02Clips move unexpectedly when editing

This is the Magnetic Timeline doing what it's designed to do: keeping clips from overlapping. When you insert or remove a clip, everything downstream adjusts to fill or accommodate the gap. If you need a clip to stay exactly where it is while you edit around it, select it and press ` (grave key). This toggles a position lock that keeps the clip in place while you edit the surrounding timeline.

03Your library is enormous for no apparent reason

Libraries grow large from two sources: optimised media (FCP-generated ProRes copies of your source files) and render files. Go to File → Delete Generated Library Files and delete render files. You can re-render anything you need later. For optimised media, only generate it intentionally: don't leave the "Optimize Media" option checked on import unless you specifically need ProRes files.

04A transition won't apply to a cut

This is the insufficient media handles problem. The clips at that cut point don't have extra frames available for the transition to use. Fix it by trimming the clip edges back slightly, reducing the transition duration, or using an adjustment clip overlay instead.

05Audio and video are out of sync

The sync issue usually appears after you've used the Blade tool or made a trim that only affected one track. Look for the red sync-offset badges that appear on clips when audio and video are misaligned. The badge shows how many frames off they are. Right-click the clip and choose Break Apart Clip Items followed by a manual resync, or use Clip → Synchronize Clips on the isolated tracks to re-lock them together.