> As an example of the benefits of this approach, one service increased its time in TCMalloc from 2.7% to 3.5%, an apparent regression, but reaped improvements of 3.4% more requests-per-second, a 1.7% latency reduction, and a 6.5% reduction in peak memory usage!

This is the stuff of performance nightmares. Anyone thinking about optimization often will get single-tracked into the performance regression there and maybe not necessarily see the improved overall performance (requests per second).