Apple has released Thunderbolt Firmware Update which provides Thunderbolt performance and stability fixes.
After launching the update, when your computer restarts a gray screen will appear with a status bar to indicate the progress of the update.
Do not disturb or shut off the power on your computer during this update.
Thunderbolt Firmware Update is available via Software Update and also as a standalone installer.
More info and download link (486 KB) here.