Restoring with standby can place a LARGE overhead on the restore of each transaction log backup file.

Leaving the database in standby means that SQL Server has to leave the database transactionally consistent (i.e. no half done transactions). This means undoing any changes made by uncommitted transactions, and writing them away so it can redo them immediately prior to restoring the next transaction log backup.

As you are backing up the logs every 2 minutes, you will have a bigger chance of having uncommitted transactions spanning log backups, therefore causing a lot of redo work before restoring the next log backup and a lot of undo work after restoring.

Are you actually using the database for any read-only work? I'm guessing not, given the frequency of backups, as users would have to be kicked off before each backup is restored.