How does using separate schemas affect SQL Server 2008 performance?
There may be an impact on the performance of the query optimizer, albeit a small one, depending on your coding style. If you reference a table without a schema, the optimiser has to try to identify the table first by checking tables within the users default schema (if there is one), then using dbo., and then everything else. If you explicitly reference the tables as schema.table, which is probably good practice anyway, then even this minor overhead will be avoided.