[Click] NAT Latency Measurement

[Latency Buster]

Does anyone has a rough estimate of the port to port latency of NAT
using Click? I'm using a combination of IPClassifier, IPRewriter and
seeing the port to port latency varying between between 20 - 30 us.
This is when the IPRewriter has a single mapping instance and I am
using PollDevice for pulling packets.

rw :: IPRewriter ( //
      		 pattern 192.16.13.24 -    192.16.14.26    - 0 1, //Active
      		 )


A related question: What's the approach to nail down the most delay
prone element along the packet path inside Click? In my instance,
Click is running on Intel Xeon processor (quad core), PCIe cards and
with 8GB RAM.


Thanks,