This is the mode in which the primary database's availability is completely independent of the redo transport service. In other words, a primary database never waits for any acknowledgment from standby destinations to complete a transaction. Thus, we don't suffer from standby network-connection problems or standby availability-related performance problems and availability problems in the primary database.
This mode is the default protection mode and the log transport service must use the ASYNC
mode with the LGWR or ARCH attribute. However, with 11g, ARCH transport is not recommended because it doesn't offer any advantage in terms of performance, and offers less data protection.
In the normal operation of the Maximum Performance configuration, the redo data, which is on the way from primary to standby, is at risk from primary database failures. The amount of data at risk is dependent to the bandwidth of the network.