You don’t mention the format/codec details of the exported clip.
Try this:
Edit the prores like you are.
Export finished edited video using “Current Settings”
Take that exported video clip master and drop it into Compressor or “Your compression software here”
Create the deliverable. Web or DVD
Look @ Vimeo or Youtube specs for uploading a HD video. Then use those settings for your compression to make a webclip.
If your pans are playing back fine in FCP, you have nothing to worry about. Also, play back a large HD file off the OS drive could have stuttered playback issues.
Chris Tompkins
Video Atlanta LLC