If these questions catch your eye, come to my workshop on test profiling and learn how to identify and fix test performance bottlenecks in the most efficient way. And let your CI providers not complain about the lower bills afterward.
I will guide you through the test profiling upside-down pyramid, from trying to apply common Ruby profilers (Stackprof, Vernier) and learn from flamegrpahs to identifying test-specific performance issues via the TestProf toolbox.