There's a cots (commercial off-the-shelf) application that I work on customizing, where a couple of pages take an extremely long time to load for certain distributions of data. (I'm talking approximately 3 minutes for a page to load in this instance... and the time is growing exponentially).
Clearly this is unacceptable but are there studies out there where I can point what acceptable response time is?
I'd like some good studies possibly that discuss response time.
Jakob Nielsen's research has answered this for any application (web apps aren't special in this regard):
So for web apps you should keep your page response times at 500 ms maximum on average near the servers, to have a web app that is a pleasure to use even with a network latency of 200-300 ms.