TFS 2012 Update 1 Hotfix

There has been a hot fix that fixes some issues in Update 1 some from the RTM. 

Issues Addressed

1. Collections that are attached to a server that is running TFS 2012 Update 1 may lose permissions
2. Group scopes may incorrectly cause permission errors
3. Severe decrease in performance after TFS 2012 Update 1 is installed
4. Identity sync jobs may fail repeatedly
5. Warehouse is not updated correctly, or fields that represent a person are not filled
6. Users can see names of collections of which they are not a member

the full KB Article is here

download here.

b.