Database Mirroring and Snapshots
asynchronous mirroring
It means, a transaction is committed on the Principal server before being copied over to the Mirror Server.  

Whereas in Synchronous Mode Principal Server send the logs to the Mirror server and waits for the signal from the Mirror Server, once the transactions has been applied to the Mirror Server only then it commits the transaction on the Principal Server. Also the transaction Safety needs to be set to full and you to have a Witness Server.

Asynchronous mirroring does not effect the performance of Principal Server whereas other operating modes in Database Mirroring will have effect on the performance of the principal server as in Synchronous Mode both the principal and Mirror server are in the same state and you can have a long Redo Queue (Pending Transactions to be rolled-Forward on Mirror Server).

Note: Asynchronous mirroring is only available in the Enterprise Edition.

Reporting with snapshot script
Have you considered SNAP SHOT Replication for the reporting purposes ???