Web site search engine response time

I wonder if anyone knows of any research dealing with user
satisfaction (as opposed to tolerance) regarding web application
response times?

I work for a software company and we are planning to introduce a
web-based support knowledgebase. It is effectively a search engine
trawling through a set of documents that describe known problems with
our products.

I am writing a spec for the application and I need to set some
performance bounds on how long it should take to run a search. My
research indicates that the maximum page load time a user will
tolerate is between 8 - 10 seconds, rising to 30 seconds with useful
feedback or incremental download.

However all that I have found seems to relate to what users will
*tolerate*. What I would like to find out is what do users find
satisfying. Does anyone know of any research that describes what
happens to user satisfaction on response times lower than 10 seconds?
If less than 1 second is very good and greater than 10 seconds is very
bad what response time is Good Enough?

Cheers

Mark