To "clean" your drawings:
With the drawing open in Master Drafting,
Go to File, Clean2D
Run the Clean by clicking on all of the buttons one at a time, top to bottom using the default settings given.
The following cleans up the drawing size dramatically:
File, Calculator,
In the text box type: "L V" (enter)
-this outputs a log to the list window of all variables attached to the drawing.
In the same text window type: "delete all"
-this will remove all of these variables except the ones listed with an * in the name.
This should clean up your drawing.