spinning beach ball from Compound clips...I think

Hi. I am working on a project with a bunch of interviews that are compound clips created by Synchronizing clips within Final Cut Pro. I'm finding now that some of these clips are causing extreme system problems (spinning beach balls). It seemed to happen right after I put one of these clips into the project sequence.
I have read a lot of others are having problems with compound clips in FCPX and wondering if any advice out there? I'm working on IMac with 16 GB Memory; 2.93 i7 Processor; version 10.8.2