Slowness Issues with Windows Authentication in SharePoint Foundation 2010 sites

All, 

We are having a strange issue with SharePoint Foundation 2010 sites where sites are very slowly loading when accessed via windows based authentication where as the extended sites in  forms authentication are loading normally.

There were no error logs or even SharePoint logs also except the images load time is showing with different load times.

Attached are the patches that were updated to the server that may be issue but not sure. Can some one please share your thoughts.

SQL connectivity b/w the server is good.there are no n/w issues except that the users are using the sites with a different domain other than the domain in which the servers were hosted.

There is a trust b/w the two domains.This was never changed and there were no issues in the last 2 years.

Thanks keshav,Share point Developer