{
    time       => $time,
    conference => $value1,
    type       => $value2,
    comment    => $value3,
}

##</code><code>##

push @AoH, { time => $t, conference => $v1, ... };

##</code><code>##

my @sorted_AoH = sort { $_->{time} <=> $_->{time} } @AoH;
foreach my $conf ( @sorted_AoH ) {
    my $time = $conf->{time};
    print ... # element
}

##</code><code>##

push @{ $hash{$time} }, { time => $time, type => $v2, ... };

##</code><code>##

for my $time ( sort keys %hash ) {
    for my $conf ( @{ $hash{ $time } } ) {
        print ... # $conf element
    }
}