By Clint Brown
When QTEXT (Quick Text) is turned on, each text and attribute object is displayed as a bounding box around the text object. Turning QTEXT mode on reduces the time it takes to regenerate drawings that contain many text objects. Use the REGEN command to display the results of QTEXT on existing text.
To toggle QTEXT on and off, simply Type QTEXT into the command line, then REGEN, as shown in the animated GIF below.
For more info see Autodesk help