[bede]

Yes I'd expect a dict-based approach to do better here. That's probably how it should be done. But --long is compelling for me because using it requires almost no effort, it's still very fast, and yet it can dramatically improve compression ratio.

[tecleandor]

From what I've read (although I haven't tested and I can't find my source from when I read it), dictionaries aren't very useful when dataset is big, and just by using '--long' you can cover that improvement.

Have any of you tested it?

[leobuskin]

I don’t think the size of content matters, it’s all about patterns (and their repetitiveness) within, and FASTA is a great target, if I understand the format correctly