The PC either spends time waiting for computation to complete or fetching data, let's say 1/10th of the time it's the latter. The time fetching Data is again split between latency and "speed" (data / transfer rate = time). Moreover RAM is only the 4th level storage in the cache hierarchy. All of these splits and fractions depend on the application and it's bandwidth hunger.
We know that Integrated Graphics progressed to the point where it completely saturates memory bandwidth, every other application maybe benefits from a split second shorter loading time. Or not at all, because higher timings negate all split seconds saved with faster rates.
It is hard to come up with random data/bandwidth hungry applications, other than perhaps public servers and real time IGP 3D graphics. CPU benchmarks bent on comparing compute performance, likely all are compute bottlenecked.