A model file larger than 100 MB takes long time to open in AutoCAD 2004 on a GPU passthrough VM.
Use AutoCAD 2014 to open this model file (this operation may last long), save the model file as a new model file of the AutoCAD 2014 version, and use the new model file later.
Opening a model file takes a long time due to software architecture or version incompatibility. If AutoCAD is single-core architecture, adding cores does not greatly accelerate the file opening speed. This problem is caused by AutoCAD version incompatibility. The model file is created using AutoCAD 2004. It takes a long time to open the model file by using AutoCAD 2014. Incompatibility problems may exist between different AutoCAD versions.