Stuttering after Sending to Final Cut Pro

After I finished my color correction and sent it back to Final Cut Pro the video doesn't play the same as it did before the C.C. Now it has a constant stuttering during playback and also when it is exported. i never had the problem before. My MacPro is a Quad core and has 10 GB of ram. It seems that that amount of memory should be more than enough to handle a little bit of Color Correction. The clips are Pro Res 422 HQ. Does that have something to do with it? Thanks for any help.