Validr is implemented by [Cython](http://cython.org/) since v0.14.0, it's 5X
faster than original pure python implemented.
Now, it's 10X faster than [jsonschema](https://github.com/Julian/jsonschema), 40X faster than [schematics](https://github.com/schematics/schematics).
benchmark result in travis-ci:
json:loads-dumps 1000
jsonschema:draft3 180
jsonschema:draft4 184
schema:default 41
schematics:default 51
validr:default 2384
validr:use-refer-merge 2106
voluptuous:default 100