Often overlooked is the "registered applications" problem.  On the command line type "-purge"  The hyphen is to get the command line version.  Next, select "R" for Regapps.  At the next prompt, accept the wild card "*".  The next prompt is to verify each registered application, and you'd be well advised to select "N" for no.  The most I've found is 114,012.  Another aspect of this problem is the registered applications propergate from one drawing to another when a drawing with some in it is xref'd into another.  All your drawing should be purged to prevent them from spreading.
 Here is a lisp routine that automates the prompts:

;Purge Registered Apps by Paul Sanucci
(defun c:pura()(command "-purge" "r" "*" "n"))

What are these entities? If each one is composed of two lines that make a cross for example, then you could make a block out of this cross and then replace each set of two lines with a single block definition.

If these entities are just POINT objects, I doubt this exercise will save much file size...

You could also WBLOCK the "Static" entities out to a separate DWG file and then XREF it back into the main drawing. When you don't need to see this stuff, you could unload the XREF, then load it back for plotting for example.

new empty drawing.

Edited by dannyboy100 - 27.May.2009 at 11:45