[ryandv]

I recall looking at New Relic reports of slow transactions that suffered from stacked n+1 query problems because the ORM was obscuring what was actually going on beneath the hood at a lower level of abstraction (SQL).

My point is it's often difficult to just visually inspect a piece of code and know exactly what is happening. In the above case it was the instrumentation and empirical measurements of performance that flagged a problem, not some a priori theoretical analysis of what one thought was happening.