Performance is the same if not better than database level replication. The database level replication is synchronous too and have to wait for the standby db to

Performance is the same if not better than database level replication. The database level replication is synchronous too and have to wait for the standby db to finish writing. If it's async, it has a worse data loss problem. The DRBD replication is fast because it intercepts the write call and then issues the network send and writing to the underlying disk in parallel. Gigabit or 10G network IO are magnitudes faster than disk seek/write. The write to disk on the standby server can happen in parallel as the primary's write to underlying disk.