Hello,
another possibility is to use the accoreconsole.exe
With this exe you can load a DWG, change it with the help of commands, also overkill and save it again.
It is also possible to load .net dlls and then use the commands they contain.
The advantage is that no user interface is loaded.
I use it to create dwg's from data or to plot many dwg's into pdf's. The speed advantage is between 30-50%.
regards Mario