Some info here but it looks like it is problematic. The possibility of slowing down the appliance is the one that worries me.
Another option is to use a SPAN or mirror port to monitor the traffic going to and from the ASA5525. You wont impact on firewall performance and it should be easy to setup a SPAN port on the switch that your firewall is connected to. Once you have your SPAN port setup you can connect NPM with DPI configured, use nProbe to get NetFlow stats or use a third party tool like LANGuardian to analyze the traffic. You can see an example of LANGuardian integrated with Orion at the link below
Hope this helps,
This is the link I always recommend:
Make sure you have firmware 8.2.1 and when configuring, set the template timeout to 1 minute.