# Each data point is stored in a separate file, so they have
# to be joined first.  I figure the shell is faster at that
# than perl.  That and I wasn't excited about managing 
# n file handles at a time, though it wouldn't be too bad.
my @lines = `join file1 file2 file3 file4`;
foreach my $line (@lines) {
  my ($time, @data) = split /\s+/, $line;
  foreach my $datum (@data) {
    # unlock the secrets of the universe
  }
}