Hi, Currently Tox our tool to run presubmits in different environments runs the job in series so can be a bit slow. There is a sister project <http://tox.readthedocs.io/en/latest/announce/release-1.4.3.html?highlight=parallel> to Tox called detox <https://pypi.python.org/pypi/detox/>. It wraps around Tox and uses greenlet to run the jobs in parallel.
On preliminary testing on my machine it was 3x faster so saved me about 4mins for each run. Found this out today so thought it'll be good to share with everyone :) Thanks Sourabh
