Recently hit a problem with Office 2007 and SharePoint integration.
Saving Office documents into a SharePoint document library was working very very slowly, even for tiny documents <10Kb, as was launching documents directly from a SharePoint document library.
After much rebooting, reinstalling and finally Googling, I found a solution to the problem, and that was (strangely) to disable the “Automatically detect settings” check box in IE.
Unchecking this option and ensuring that the “Bypass proxy server for local addresses” option was also checked solved the problem.

Thank you very much. I was having very bad performance when saving Infopath 2010 forms to Sharepoint 2010. After changing you recommended settings, it saves documents in a flash !
Thanks a lot, man!
BTW, I’ve wrote a step-by-step instructions on how to change this settings on all workstations with group policy:
http://soonts.livejournal.com/349386.html
Thank you so much for this, been pulling my hair going crazy over the slow performance in sharepoint and now it goes almost instantly, thank you kindly! =)