AutoCAD Visual LISP / AutoLISP :: Remove Hidden Data And Reduce File Size

I am trying to reduce the drawing file size.  This is for uploading the drawings to AutoCAD WS.  AutoCAD WS doesn't display or edit a drawing that is over 15MB. Unfortunately some of our drawings are over 15MB even after I have removed the background and others and have purged. I believe the reason why a drawing can be so big has to do with each object (grouped object) has a ton of information on it. For example, the properties of a typical object is like this:

( (-1 . <Entity name: 7ffffbece60>) (0 . "PRCD_FITTING") (5 . "145B6") (102 . "{ACAD_XDICTIONARY") (360 . <Entity name: 7ffffbece70>) (102 . "}") (330 . <Entity name: 7ffffbf59f0>) (100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "BON-SupplyMP-3.0-4.0 RECT") (62 . 1) (100 . "CPrcdEntity") (280 . 10) (90 . 601861454) (70 . 24058) (70 . 4567) (280 . -65) . . Skip 3000 lines here for clarity . (90 . 0) (90 . 0) (90 . 0))

You can see from above that the list of properties are huge.  All I really need are the visible parts of the object.  This means most of the info above are junk.I try to reduce the size of object by exploding all the objects on the drawing.  This sort of work in the sense that the file size of a test drawing is reduced from something like 8MB down to 6MB.  But I am expecting far more reduction than this.  The reason why I expect far more reduction is that the total number of lines of the exploded items of the same object mentioned above is reduced from 3000+ lines to only 300 lines as shown below:
 
( (-1 . <Entity name: 7fffe8654f0>) (0 . "LINE") (330 . <Entity name: 7ffffa1b9f0>) (5 . "3B11F") (100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "BON-SupplyMP-3.0-4.0 RECT") (62 . 1) (100 . "AcDbLine") (10 4188.87 -423.095 156.0) (11 4188.87 -387.095 156.0) (210 0.0 0.0 1.0))( (-1 . <Entity name: 7fffe8655f0>) (0 . "LINE") (330 . <Entity name: 7ffffa1b9f0>) (5 . "3B12F") (100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "BON-SupplyMP-3.0-4.0 RECT") (62 . 1) (100 . "AcDbLine") (10 4248.87 -453.095 156.0) (11 4212.87 -453.095 156.0) (210 0.0 0.0 1.0)).. Skip 250 lines here for clarity.( (-1 . <Entity name: 7fffe865260>) (0 . "MTEXT") (330 . <Entity name: 7ffffa1b9f0>) (5 . "3B0F6") (100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "BON-SupplyMP-3.0-4.0 RECT-ANNO") (62 . 1) (100 . "AcDbMText") (10 4193.39 -418.589 150.0) (40 . 3.0) (41 . 19.8) (46 . 0.0) (71 . 1) (72 . 1) (1 . "\Fdim.shx;\W0.7000000000;\T1.0000000000;\o\l24X30THRT") (7 . "BonDuctTXT") (210 0.0 0.0 1.0) (11 1.0 1.46161e-017 0.0) (42 . 17.5) (43 . 3.0) (50 . 1.46161e-017) (73 . 1) (44 . 1.0))

Therefore, I am expecting a 10-to-1 reduction, not just a 1/4 reduction.I am wondering there may be hidden data on the drawing that are left behind after I have exploded the objects. if there is a way to get rid of the hidden data?