while (<FILE>) {
    push @lines, $_;
}

##</code><code>##

push @_,$_ while <$fh>;

##</code><code>##

@lines = <FILE>;

##</code><code>##

@line= <$fh>;

##</code><code>##

Benchmark: running list_io, split_slurp, while_io, each for at least 5 CPU seconds...
              Rate    while_io     list_io split_slurp
while_io    1629/s          --         -5%        -40%
list_io     1722/s          6%          --        -37%
split_slurp 2725/s         67%         58%          --