Stored Procedure
Provided that all data required by a transaction is in memory, the stored procedure can execute very fast, without waiting for any network or disk I/O.
A database is often much more performance-sensitive than an application server, because a single database instance is often shared by many application servers. A badly written stored procedure (e.g., using a lot of memory or CPU time) in a database can cause much more trouble than equivalent badly written code in an application server.