Sorry Will, but I will never understand these questions. No matter what, performance is based on lots of factors besides the code in Spring Integration or other frameworks, libraries, products. So any numbers you see given, can and usually are fabricated. Never trust performance metrics/specs out there. Maybe they are true maybe they aren't. But it is always your mileage my vary.
I never ask about performance when I go out and choose a product, because I can tell more about the product in other ways, like when I start using it, how easy is it to understand, how quickly can I start being productive. How popular is it. I have already found that the easiest, most popular, most productive products also tend to never have performance problems.
I would say it is almost 99.99% of the time the user/developer that makes something run slow, not the product. Maybe 10 years ago it was different, but today?