Final Cut Pro glitches when importing AVCHD footage

I encountered an issue recently where Final Cut Pro will jitter and glitch out every half a second or so when importing AVCHD footage from a Sony HD camcorder. I eventually tracked down the error thanks to some google searching and it turns out that Perian is the culprit. Apple even have a couple of knowledge base articles about it: Final Cut Pro/Express: Ingested AVCHD clips are sometimes distorted Final Cut Pro, Final Cut Express: Unexpected quit during AVCHD ingest If you disable Perian in the System Preferences before launching Final Cut Pro, it’s all good.