is there a performance hit using flush() ?

I am looping through a few thousand records and would like to display the results every loop. Eg: while($row = mysql_fetch_object($sql)): echo "Hi $row->name<br>"; flush(); endwhile; A simple example - but you see what I am trying to achieve. Perhaps a more realistic example is displaying the results of a mail program as it fires off mail to hundreds of members in a database. Will this slow down the execution of the script at all - or much? Regards, Matthew Delmarter