Save individual placemarks, shapes, or entire folders by right-clicking the item and selecting Save As... from the pop-up menu.
Use the 'File' dialog box to save the placemark or folder to your computer. Enter the name for the new file, and click Save in the dialog box. The placemark or the folder is saved to that location with an extension of '.kmz'.
You may want to use this feature if:
You want to share the saved data with other Google Earth users. You can email any placemark, shape, or folder to another Google Earth user from within Google Earth, but you can also email any KMZ file located on your computer to a Google Earth user. In addition, you can post a KMZ file to the Google Earth BBS where other Google Earth users can view the information, or you can serve the file on your own web server or from any network location. See Sharing Places Information for details.
You have so many places in your My Places folder that Google Earth startup is slow. Each time you start Google Earth, all the places data is processed during startup, even if it is not turned on in the 3D viewer. Holding a large amount of data in the 'My Places' folder can impact the performance of Google Earth, depending upon your computer. By saving folders to your hard drive, you can improve Google Earth performance by then deleting the data from your My Places folder once they are saved to disk. You can always open the data you save at any time.