An error or warning message appears and I view it in the Message window. If the error is expanded, by selecting the + symbol to the left of the message to show the full content and it is an extremely long message, the interface slows down as if it hangs and becomes extremely slow.
Placer is unable to place hundreds of Macros for one reason or another. If the error message is expanded, it lists the entire set of macros that could not be placed.
[Place 30-365] The following macros could not be placed:
(Listing of all of the macros it could not place)
You can return the responsiveness to the GUI by minimizing the message if it is expanded.
This issue is fixed in Vivado Design Suite 2012.4.