Another thought would be to look at the size of your redo logs and how many groups you have. If you are doing a large number of log switches and your redo logs are relatively small, you could increase the size of the logs to give the archiver more time to do it's work and to reduce the overhead of the log switches.
How big are your current redo logs and how often do you switch logs?
As a rule of thumb, your log switches should not be shorter then 30 minutes. If it is sooner then that, figure out how often they switch and increase the size of your redo logs to get the switch time to 30 minutes. If you need help with how to make your logs bigger, ask in this thread.
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