Here is an example where there is 6.5+ minutes of overhead to run 40s of tests:

https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20Production%20Engine%20Drone/108269/overview

This may be an artifact of the long source checkout time when there is a cold cache, but even in the case of a warm cache the checkout time appears to be around 30s, so including the other steps, there will still be more overhead than time running tests.

cc @keyonghan @godofredoc @eyebrowsoffire @yjbanov