FCP 7 workflow slowdown
Working in FCP7 on an iMac, I'm almost finished a week's worth editing a 3 minute video in DVCPROHD 1080pA24. Suddenly, yesterday, everything slowed down. Examples: whenever I switched from viewing on the Canvas to fullscreen and back again, I get the spinning beachball for at least 25 seconds and the message, "Preparing Video for Display"; whenever I shift a video clip in the timeline, the same thing happens. Needless to say, this makes the workflow almost impossible. Luckily, I'm almost finished the project but there maybe revisions and I dread going through this again.
I've checked my other FCP projects and this isn't happening.
Does anyone know what could be causing this slowdown and what I could do to fix it? What opening another project and dragging my sequence and select take bins into it do that?
Phil