"buffer not emptied" #533

Hi. Today I noticed an unusual fact. While scanning (simultaneously passing the output to a queued pipe with grep, or saving the output to the file with -oG), the scan results are not saved until I stop the program or they "pile up" quite a bit of IP. It is as if masscan does not empty the buffer until it reaches a certain "threshold" .... is that normal !? and how can this be avoided?

Thanks