You're not alone.I've the same problem - flash I/O can take 100% of CPU.
Per-connection.I that per-client or per-connection?...a true round-robin option when it comes to the src-address for the web proxy.
I just set up MacOS 10.6.8 as an L2TP/IPSec client to ROS 5.8.ROS 5.8
IPSec and IPSec/L2TP does not work with Mac OS X. Works fine with windows and linux.