Ah, I see. That was another case of grabbing code from another node without checking enough. This code runs (by my benchmark) 33% faster than the old split_int:

#...
split_pack => sub {
            my @sorted = map { join '.', unpack("CCCC", $_) }
                sort { $a cmp $b }
                map { pack("CCCC",split /\./) } @ips;
        },
#...
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