Tell Capybara to wait until iframe has loaded (is ready)

Is there an elegant way to do this? At the moment i just use a custom step "And wait 10 seconds" to be absolutely sure, there is enough time for the iframe to get ready. I don't want this feature to fail on my underpowered CI VM because of a small network issue or cpu spikes. But this means that the feature suite wastes a lot of time, and as you know, if the test suite takes a long time, one often doesn't bother to run it outside the CI server.