atilika/kuromoji — pull request #3 by masaruh (2013-06-27 03:57:42+00:00)
Title: Don't use String#replace and String#split during TokenInfoDictionaryLook...

They are slow since they use regular expression and need to compile Pattern every time.
Here is brief test result https://github.com/masaruh/kuromoji/commit/ec0de23cbccf675f05bcf903f98c0b9a95b07f51.