LandXML import size

[mkt]

Hi

Something I don't quite understand here.

In a blank drawing, I have imported LAS files to a point cloud, created a surface from this. Dwg file size 60 MB.

In a new blank drawing I have created a referance to the surface. Dwg file size 30 MB.

Now this is all fine and dandy, BUT.

Export the surface to LandXML. File size 90 MB. 

Change the export setting to points only. File size 34 MB. 

Okay then import surface to Civil. File size 87 MB. (With create snapshot after import)

With snapshot after import set to "off". File size 59 MB. 

Why does the dwg increase so much in size, and what can I do to avoid it?