Davis Montenegro has done some investigation of how to do early binding to the COM interface in various languages and posted a description in the Help forum:
http://sourceforge.net/p/electricdss/discussion/861977/thread/b320652e/
There is also a report of his study results attached to the posting as well as in the Doc Folder:
https://sourceforge.net/p/electricdss/code/HEAD/tree/trunk/Distrib/Doc/COM%20Speed%20Comparison.pdf
The source code to the OpenDSSDengine.DLL is posted here:
https://sourceforge.net/p/electricdss/code/HEAD/tree/trunk/Source/DDLL/
User Manual for the DLL is here:
https://sourceforge.net/p/electricdss/code/HEAD/tree/trunk/Distrib/Doc/OpenDSS_Direct_DLL.pdf