Inter-HA L7 persistence updates increase both CPU and network load. CPU is utilized to process the data and send updates to the partner device. Network load is naturally consumed in the process of sending the updates. This can be mitigated at the interface level by migrating the multicast interface to a direct connection between the HA pair. This is always the recommended approach when enabling this setting. Failing to implement this can quickly saturate an interface since increases in production traffic will increase the number of updates needed. This can be an insidious problem as during periods of low traffic there will be no indication of this problem. Please consult with a Customer Support Engineer for further information and guidance if you are interested in implementing this feature.