We installed SP1 this weekend, after all user complain about a site collection which is very slow.
We were able to isolate the problem to permissions which is very weird.
If somebody is farm admin, or its in the web application policy with full control, the website even with big views that returns 2000 items, it takes 5 seconds to load.
Once I remove my self from web application user policy, or farm administrator, then the same pages become very slow to me (50 or 60 seconds).
So, we isolated the problem, no idea about the cause, any idea is welcome.