Speed of shutil.copy vs os.system("copy src dest") in win32

[Russell Warren]

I just did a comparison of the copying speed of shutil.copy against the
speed of a direct windows copy using os.system. I copied a file that
was 1083 KB.

I'm very interested to see that the shutil.copy copyfileobj
implementation of hacking through the file and writing a new one is
significantly faster... any clue as to why this is? I figure I'm
missing something here.

Does os.system launch a cmd shell every time?
[0.99285104671434965, 0.68337121058721095, 0.84528340892575216,
0.87780765432398766, 0.8709894693311071][2.8546278926514788, 2.3763950446300441, 2.4444609580241377,
2.4392499605455669, 2.4446956247265916]

 

[Tim Roberts]

I just did a comparison of the copying speed of shutil.copy against the
speed of a direct windows copy using os.system. I copied a file that
was 1083 KB.

I'm very interested to see that the shutil.copy copyfileobj
implementation of hacking through the file and writing a new one is
significantly faster... any clue as to why this is? I figure I'm
missing something here.

Does os.system launch a cmd shell every time?

Yes. That's in the documentation.