If I understood the article correctly, the ~1ms cost came from having rsyslog running, not from printk. Killing rsyslog led to a ~1ms speedup, but it was removing printk() that led to the rest.<p>Printing to the console on the RPi could involve either or both of the serial port and the software-character-generator-based text-mode video output. Depending on screen resolution, the video output might be quite slow to print to, especially if it had to scroll a line, depending on exactly how it&#x27;s implemented.