You can also test your app with apache stress test. Cockpit is doing very well actually. I got 700 api response/sec on my virtual machine (2gb ram, 4 core cpu CentOS) without API cache add-on.
Example usage:
ab -n 5000 -c 200 http://yourdomain.com (without SSL)
abs -n 5000 -c 200 https://yourdomain.com (with SSL)