use Benchmark qw(:all);
                                                                                
timethese(
    100,
    {
        'By File Size' => sub {
            open XLSFILE, "x";
            my $xlsdata = do { local $/ = \-s (XLSFILE); <XLSFILE> };
        },
        'Plain Slurp' => sub {
            open XLSFILE, "x";
            my $xlsdata = do { local $/; <XLSFILE> };
                                                                                
        },
    }
);