The problem is that you are processing (splitting) @flab lines 14.4 million (200 @flab lines x 72,000 LONG_LIST lines = 14.4 million splits) times, when you should process them only 200 times. You should pre-process the @flab lines and put them into a usable data structure so that, once you've gotten a line from LONG_LIST ready, it's just a straight-up comparison.

I'm not going to write your code for you, but you basically need to move

#split each @flab line into two fields ‘Name’ and ’Title'
my @match = split (/\t/,$line);
[download]

so that it happens before you enter your while loop to work on LONG_LIST. I'll be very surprised if that doesn't make a huge difference in the time it takes to run your script. It would be very much appreciated if you would let all of us know your results after the change.