this is just a guess but ... your timing it wrong ... that is when you copy the file it opens the file and reads it all into memory so that when you paste you only create a file and dump your memory contents
in python
copied_file = open("some_file").read()
is the equivelent of the ctrl + c copy
then
with open("new_file","wb") as f:
f.write(copied_file)
is the equivelent of the ctrl + v paste (so time that for equivelency ....)
if you want it to be more scalable to larger data (but its not going to be as fast as ctrl+v /ctrl+c
with open(infile,"rb") as fin,open(outfile,"wb") as fout:
fout.writelines(iter(fin.readline,''))