NSRegularExpression performance bug or bad code?

Looking at the Benchmarks Game RegexDNA test, Swift's performance seems
rather poor. Being new to Swift, I'm hoping someone can tell me if the
problem is NSRegularExpression or is program just poorly written.
http://benchmarksgame.alioth.debian.org/u64q/program.php?test=regexdna&lang=swift&id=2