Thanks!

Yes, we are aware that Ohm's batch parsing performance is not great. In practice, it has been fast enough for our uses -- especially since we implemented incremental parsing. With incremental parsing, Ohm's ES5 parser can be as fast as hand-optimized parsers like Acorn.

But you're right, there is definitely room for improvement. So far, we have been much more concerned with making Ohm easy to learn and pleasant to use. I would certainly be happy to have contributors who are interested in improving our batch performance.