On a Quantum Force (9000/19000/29000) or Lightspeed appliance, 100% CPU utilization on the SND cores (at least as reported by Linux-based tools such as vmstat or top) does not necessarily indicate congestion as UPPAK is enabled, which uses poll mode instead of interrupts to grab traffic for processing.
Please provide more information about your appliance model number and Jumbo HFA version.
Attend my online "Be your Own TAC: Part Deux" CheckMates event
March 27th with sessions for both the EMEA and Americas time zones