Displaying multiple CDI sections in 3D can be very memory hungry, depending on tehe resolution of your input data. An alternative to displaying a section group or multiple sections in 3D is to batch print the CDI sections while displayed in a single Section Profile display and display the resultant Located Images of the sections in 3D.
To quickly create these located images select the File>Batch Hardcopy Wizard menu option while the section profile display (showing the gridded sections) is the active window. On page 2 of the Batch Hardcopy Wizard interface choose the hardcopy image to be "Located Image files on disk" and specify how many survey lines you want to be processed. This will result in 1 located image (.EGB) file and a series of images (.PNG, .JPG, etc) for each line you chose to batch print. 
In a new 3D display window add a Located Image data object and load the .EGB file that was created during the printing process. Alternatively drag and drop the .EGB file from a Windows Explorer page into the 3D display window.