On my Macbook with way too much running, I get about 800MiB/s in Python2 with your script, but 1.12GiB/s with this Python3 script: import sys s =

On my Macbook with way too much running, I get about 800MiB/s in Python2 with your script, but 1.12GiB/s with this Python3 script: import sys s = b'y\n' * 1024 write = sys.stdout.buffer.write while True: write(s) # 1.12GiB/s Plain old yes comes in at 22Mib/s. The Python3 docs say to "use the underlying binary buffer object" when reading or writing binary data. https://docs.python.org/3/library/sys.html https://docs.python.org/3/library/sys.html