As Travis-CI is evolving and extending its feature set it naturally becomes nicer and nicer to use. I recently read this article about "Speeding up the build". A build for the Django project I am working on takes ~25-30 minutes. Almost half of this time is spent on creating the virtualenv, i.e. installing the project's requirements. The other half of the time is used for the actual test run.
There are efforts on cutting down runtime for tests. Yet, I was wondering whether a bigger speed-up was up-for-grabs by caching or bundling the project's requirements. As for Plone there seem to be some options as it uses buildout. I was also looking at WAD. Of course, when caching the requirements they will need to get invalidated upon a requirements update.
Has anyone made any Travis build speed improvements for a (Django) project by cutting down setup time?