why opencascade' speed to read stl file not as fast as freecad

In my application now I use freecadcmd to read the stl 's width、height、volume and area, and the code is bellow:

import sys, Mesh, string, json,os
from FreeCAD import Base
filename = sys.argv[2]
name_arr = filename.split('.')
mesh = Mesh.Mesh(filename)
obj["area"] = mesh.Area
obj["volume"] = mesh.Volume

as it as ap.py  and call it by : freecadcmd ab.py  xxxx.stl

But now I want to use occ , and the c++ code is bellow:

int main(int argc, char *argv[]){
    if(argc <= 1){
        std::cout<<"occstl wrong arguments count!"<<std::endl;
        return -1;
    }
    Standard_CString aFileName = argv[1];
    TopoDS_Shape shape;
    StlAPI_Reader reader;
    reader.Read(shape,aFileName);
    GProp_GProps system;
    BRepGProp::VolumeProperties(shape, system);
    Standard_Real volume = system.Mass();
    std::cout<<"volume:"<<std::to_string(volume)<<std::endl;
    BRepGProp::SurfaceProperties(shape, system);
    Standard_Real area = system.Mass();
    std::cout<<"Area:"<<std::to_string(area)<<std::endl;
}

Then  I use the same stl file , the app use freecadcmd  cost  three second, but the occ c++ code cost about 2 minutes. Is there any problemes in my c++ code ?

Forgive me but I don't use c++ very well , can anyone explain why the difference of speed is so big?