CPUHOG errors are simply an informational message that indicate a process has been running longer than the default timer (2000ms). The idea is to let the user know that a certain process may be taking too long to complete. It can be an indication of a software bug, but can also be induced simply by load conditions.
In your case, we see that the "crypto sw pk proc" has been busy. This indicates that we're taking awhile to send out software encrypted ipsec packets. Encryption is particularly processor intensive without any hardware accelleration. Therefore, if your crypto utilization is high enough on this device, we could expect to see some degree of CPUHOG errors and poor crypto performance. Based off of your description, I would guess that it's the crypto traffic rate that is higher on this particular device.