1) the <number of lines> parameter in /loadbuf is optional. If not specified, /loadbuf loads the entire file. So can save some processing time by not letting mirc calculate $lines().

2) You can do it in one /filter:
Code:
filter -foa mp3.txt $dname N

/.timerQ 1 0 echo /.timerQ 1 0 $timer(Q).com