Comment 1 for bug 721290

Well, if commenting out krb5 speeds it up, this sounds like a pam_krb5 issue rather than a pam issue, doesn't it? pam doesn't pull in krb5 automatically, you must have configured this. :)

krb5 slowness is usually an indication of network problems. It might even be a sign of a bug in ipv6 name resolution on your network; and as eglibc was also uploaded this week, it might be a regression there. But I don't believe there are any changes to pam in the new version that would have caused krb5 slowdowns. I'm running the new package with krb5 just fine on my own systems and don't see this symptom.

the upgrade of pam at the same time is almost certainly a coincidence.