You've put the table loop on the outside, which is good. If it was on the inside, you'd be compiling a lot of regexps for nothing. But it can be taken a step further. 

my $tableList = map qr/$_/i,
                join '|',
                map quotemeta,
                @tableList;

for my $Q (@fileList) {
   push @tableUsed, $Q =~ /$tableList/g;
}

[download]

The OP might want to remove duplicates from @tableUsed. 

my $tableList = map qr/$_/i,
                join '|',
                map quotemeta,
                @tableList;

my %tableUsed;
for my $Q (@fileList) {
   for my $W ($Q =~ /$tableList/g) {
      ++$tableUsed{$W};
   }
}

my @tableUsed = sort keys %tableUsed;

[download]

In reply to Re^2: comparing 2 lists by ikegami
in thread comparing 2 lists by dhudnall

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