Tech-Hounds published an article examing the peculiarities of replays / timedemo runs and real world gameplay test.

Performance evaluations are never easy and the argument of using synthetic and real world benchmarks is one that's neverending among reviewers, the general public and even manufacturers. While they are not the perfect tool to capture performance a hardware will offer, they do give us an idea of hardware performance. In this article, we took the time to learn the peculiarities of the old, still widely used replay / timedemo runs and gameplay testing sessions.

Benchmarking On Trial