Cool! Didn't know that marking database read-only gets me some performance gains.
What if I make just one filegroup read only? Would that give me the same benefit for the tables, residing in that filegroup? In other words, can SQL Server disable locking on just a single file group? I am guessing it should be able to... However, how would it then handle a scenario where a table resides in a readonly filegroup, but one of its indexes is in readwrite filegroup? Would it still try to place latches on the index pages, even though the table and hence the index can't change?