Good series of blog posts on the LMAX trading platform’s performance testing strategy — they capture live traffic off the wire, then build statistical models simulating its features. See also http://epickrram.blogspot.co.uk/2014/07/performance-testing-at-lmax-part-two.html and http://epickrram.blogspot.co.uk/2014/08/performance-testing-at-lmax-part-three.html .
The modern state system is built on a bargain between governments and citizens. States provide collective social goods, and in turn, via a system of norms, institutions, regulations, and ethics to hold this power accountable, citizens give states legitimacy. This bargain created order and stability out of what was an increasingly chaotic global system. If algorithms represent a new ungoverned space, a hidden and potentially ever-evolving unknowable public good, then they are an affront to our democratic system, one that requires transparency and accountability in order to function. A node of power that exists outside of these bounds is a threat to the notion of collective governance itself. This, at its core, is a profoundly undemocratic notion—one that states will have to engage with seriously if they are going to remain relevant and legitimate to their digital citizenry who give them their power.