How do I set up simulation environment without having to re-run it on every scenario?

I need to test a complex application that doesn't follow usual Rails standards. At the moment I have several features that have following in their background:

When I set up default environment

That step takes very long time. There is no point to run it before every scenario. Ideally I would like to run it before certain features and then use database cleaner gem to roll back to the default state.

How do I do it?