broadly I agree with this approach... I'm not 100% happy with the metaphor of pushing bottlenecks around, but I do like the conceptualization of chasing bottle

broadly I agree with this approach... I'm not 100% happy with the metaphor of pushing bottlenecks around, but I do like the conceptualization of chasing bottlenecks. It's certainly possible to do this, for example if the parse/analysis code were fairly inefficient but the previous bottleneck was IO, then it's not so much that the bottleneck shifted, it's like you widened one bottleneck and discovered another one. I model all the bottlenecks as already being there and it's just that sometimes some hide the others. The specific case where you "blindly" optimize code without running it through a profiler first are those cases when the code is still so rough you can just identify bottlenecks by inspection.