Having integrated with these kind of systems, they aren't up to internet-scale traffic. Apart from raw capacity they are usually architected for transactional c

Having integrated with these kind of systems, they aren't up to internet-scale traffic. Apart from raw capacity they are usually architected for transactional consistency, not large indeterminate numbers of concurrent users. This is why we have things like ESB's and async enterprise integration patterns. I'd be surprised if those weren't already in place on this project but bet it's really poorly done. My money is on a totally manual test process which means a deployment misses loads of cases and takes weeks and where a load test is 10 guys in India hitting f5.