Do you know which method of Load-sharing they are using? As Mr. @Timothy_Hall kindly pointed out to me in prior conversations, you can use SecureXL in Load-Sharing Unicast mode. I had definitely misunderstood that and thought any use of Load-sharing precluded you from enabling SecureXL.
I would suggest starting by going into cpconfig and changing the allocation of SND's / FWK's. If it is a 20 core box, the default configuration would have been 18 FWK Instances and 2 SND's. (So enter 18 at the prompt in cpconfig).
If you find you are able to enable SecureXL, you may want to consider monitoring usage with SecureXL on and considering changing it to 16 FWK instances and 4 SND's. If SecureXL isn't an option for sure, you probably want as many FWK instances as possible since that's where all your traffic is being processed.
R80 CCSA / CCSE