The new Final Cut has been radically redesigned. In fact, it looks and works a lot like iMovie, all dark gray, with “skimming” available; you run your cursor over a clip without pressing the mouse button to play it.

Once you’re past the shock of the new layout, the first thing you’ll notice is that Apple has left most of the old Final Cut’s greatest annoyances on the cutting-room floor.

First — and this is huge — there’s no more waiting to “render.” You no longer sit there, dead in the water, while the software computes the changes, locking up the program in the meantime, every time you add an effect or insert a piece of video that’s in a different format. Final Cut X renders in the background, so you can keep right on editing. You cannot, however, organize your files or delete clips during rendering.

Second, in the old Final Cut, it was all too easy to drag the audio and video of a clip out of sync accidentally; little “-1” or “+10” indicators, showing how many frames off you were, were a chronic headache. But in the new Final Cut, “sync is holy,” as Apple puts it. Primary audio and video are always synced, and you can even lock other clips together so that they all move as one.

In fact, an ingenious feature called Compound Clips lets you collapse a stack of audio and video clips into a single, merged filmstrip on the timeline. You can adjust it, move it and apply effects as if it were a single unit, and then un-merge it anytime you like. Compound Clips make it simple to manage with a complicated composition without going quietly insane.