detox is the distributed version of tox. It makes efficient use of multiple CPUs by running all possible activities in parallel. It has the same options and configuration that tox has so after installation can just run:
detox
in the same way and with the same options with which you would run tox, see the tox home page for more info.
Additionally, detox offers a -n or --num option to set the number of concurrent processes to use.
Please file issues as "tox" issues using a "detox: " prefix in the issue title.
detox runs on python2.7 and python3.4+ (but supports creation of all environments supported of the underlying "tox" command)