attoparsec now seems to be slower than joyent http parser

Since the blog post 2014 http://www.serpentine.com/blog/2014/05/31/attoparsec/ things seem to have changed. For another project in benchmarked a few http parsers are posted the results here https://github.com/rust-bakery/parser_benchmarks/issues/25

I get `99290 / 64687 = 1.53x` more slowdown on one test and `759000 / 282021 = 2.69x` on the other test (measuring in ns) compared to joyent more recent version of http parser.

Perhaps there is some more room for improvement? I've been looking at core, but with my untrained eye i couldn't make much of it. All i could find was potentially https://github.com/bos/attoparsec/issues/152