Hi Terry,
These are the steps you should take:
1. Completely disconnect the mini converter from your mac. This converter is not suited for monitoring broadcast video from the Thunderbolt port, it just delivers a computer preview quality and it drains the resources from your TB ports. Dump it or use it elsewhere. If you want true SDI or HDMI video quality monitoring from the TB connectors you should consider the AJA T-TAP, the AJA IoXT or similar boxes from BlackMagic or Matrox. Always make sure to have the latest drivers installed for these boxes.
2. Once the converter is physically disconnected play back your video and see if you still have the stuttering. If so:
- Do a repair permissions on your system drive
- Reset your FCP X preferences. In 10.1.2 the best way to do this is to launch FCP X while holding down the ALT+CMD keys. A message will pop up asking you if you want to reset the preferences, just confirm and let FCP X launch.
Play your video again to check the stuttering. If it still persists we will need additional information:
- What version of Mavericks are you running?
- What is the nature of your footage? Are you editing with the native media or are you working with optimized media?
- Do you have Background Rendering turned ON?
- Is your FCP X playback set to Better Performance or Better Quality?
Best wishes,
Ronny