Slightly more complex code with tests beats code with no tests every time, and it works just fine. Having 1 more class or function call is not exactly what makes an impact on workload. If you are optimizing your application by reducing function calls you are doing it wrong. But tell me, how does not having tests work out for you? Can you modify old applications, or applications that you didn't develop alone, with a high degree of certainty that you didn't break things in the least expected places?