10x dxf export speed (#1773)

Author: SDI8

cadquery/occ_impl/exporters/dxf.py

@@ -197,8 +197,6 @@ def add_shape(self, shape: Union[WorkplaneLike, Shape], layer: str = "") -> Self
                     dxfattribs=general_attributes
                 ).apply_construction_tool(entity)
 
-        zoom.extents(self.msp)
-
         return self
 
     @staticmethod
@@ -394,4 +392,5 @@ def exportDXF(
         for s in w:
             dxf.add_shape(s)
 
+    zoom.extents(dxf.msp)
     dxf.document.saveas(fname)