You can load only geometry from model space views that are saved in the current drawing.
If you do not select a layer or layers to load, no layer geometry is loaded into the drawing but all drawing layers exist in the drawing. If no layer geometry is specified to load into the drawing, no geometry is loaded even if the geometry from a view is specified to load. If you draw objects on a layer that is not loaded, you may be drawing on top of existing geometry that is not loaded in the drawing.
If the drawing contains a spatial index, you can select the Use Spatial Index option.
A spatial index is a list that organizes objects based on their location in space. A spatial index is used to locate the portion of the drawing that is read, reducing the time required to open the drawing.
If the drawing contains xrefs that you don't want to load, select Unload All Xrefs on Open.