Andrei Alexandrescu needs to read this

[welkam]

I watched many of his talks and he frequently talks about 
optimization that produce single digits % of speed up in 
frequently used algorithms but doesnt provide adequate prove that 
his change in algorithm was the reason why we see performance 
differences. Modern CPUs are sensitive to many things and one of 
them is code layout in memory. Hot loops are the most susceptible 
to this to the point where changing user name under which 
executable is run changes performance. A paper below goes deeper 
into this.

Producing Wrong Data Without Doing Anything Obviously Wrong!
https://users.cs.northwestern.edu/~robby/courses/322-2013-spring/mytkowicz-wrong-data.pdf