If you have a Final Cut sequence with multiple layers and/or effects (why?!!) you may find that it is very slow to export. One solution is to ‘nest’ the sequence inside another sequence; this allows Final Cut to pre-process all the layers/effects before the export stage, making it quicker to export.
1. MAKE A NEW SEQUENCE IN THE BROWSER
2. DOUBLE-CLICK TO OPEN THE NEW (EMPTY) SEQUENCE
3. DRAG YOUR ORIGINAL SEQUENCE FROM THE BROWSER INTO THE NEW TIMELINE
4. EXPORT US USUAL, USING File > Export > Using QuickTime Conversion