EnglishspaCy is a rather new library (written in Python and Cython) for performing various NLP-related tasks such as tokenization, POS-tagging and syntactic parsing. The authors claim it’s faster (in some cases a lot faster) than other common solutions such as NLTK or Stanford’s CoreNLP and peer reviews seem to corroborate these claims.
spaCy is English-only for now. If you’re working on performance-intensive NLP tasks and if that’s no deal-breaker for you might want to check it out. The source code is available here.