A common advice is to focus optimization in the few places where it matters, such as in the middle of tight loops. Sqlite is in an interesting situation in than

A common advice is to focus optimization in the few places where it matters, such as in the middle of tight loops. Sqlite is in an interesting situation in than almost all their code could be called in the middle of somebody's tight loop. The same applies to many libraries, operating systems, VMs, etc, but not to most applications.