Improve performance of Writing a file - Python 3.4 -

i not versed python, based on knowledge , browsing wrote script mentioned below, script looks files in c:\temp\dats folder , writes in c:\temp\datsoutput\output.text file, reason code running terribly slow, can advise me improve have better performance?

    import os     = open(r"c:\temp\datsoutput\output.txt", "w")     path = r'c:\temp\dats'     filename in os.listdir(path):         fullpath = path+"\\"+filename         open(fullpath, "r") ins:                 line in ins:                     a.write(line) 

two speedups. first, copy whole file @ once. second, treat files binary (add “b” after “r” or “w” when opening file.)

combined, runs 10x faster.

final code looks this

import os = open(r"c:\temp\datsoutput\output.txt", "wb") path = r'c:\temp\dats' filename in os.listdir(path):     fullpath = path+"\\"+filename     open(fullpath, "rb") ins:             a.write(ins.read())