How would you normally go about stress-testing a Django app like that to look into bottlenecks?
All the articles and talks I see on scalability and optimization use production servers as examples, but as you way, you want to optimizing for traffic instead of responding to it.
There's no way to stress-test a complex web realtime system without actually running it on the real hardware.
You'd expect very nonlinear behavior between number of users, response time and number of machines used.
Not being a part of Disqus, the only way I see to "predict" performance beyond the load already seen is to try and use past data from the current real system.
All the articles and talks I see on scalability and optimization use production servers as examples, but as you way, you want to optimizing for traffic instead of responding to it.