Identity column as clustered index bad idea?
I usually use an identity column as clustered primary key. However in some (rare?) cases this is not ideal because of the LastPageInsertLatchContention. This happens if a table is heavely filled with data. Because of the identity key all this INSERT's wants to write the last page of the table (index). So this page can be locked and the performance may be better with another solution.

See 


http://dangerousdba.blogspot.ch/2011/10/bit-reversion.html
http://blogs.msdn.com/b/sqlserverfaq/archive/2010/05/27/monotonically-increasing-clustered-index-keys-can-cause-latch-contention.aspx
http://www.sqlpassion.at/archive/2014/04/15/an-ever-increasing-clustered-key-value-doesnt-scale/


for details.