If you find yourself having to disable SecureXL in R80.20+, the best course of action is to open a TAC case so the problem can be identified and fixed. Disabling SecureXL long-term in R80.20+ is not a good idea and will eventually get you into further trouble.
However in the interim, there is a workaround for disabling SecureXL upon bootup on R80.20+ in this thread:
https://community.checkpoint.com/t5/Enterprise-Appliances-and-Gaia/R80-20-SIT-Tunnel/m-p/28139
While your box may be "strong enough" to handle the workload without the SecureXL functions throughput acceleration and rulebase accept templating (session rate acceleration), keep in mind that disabling SecureXL will also disable automatic interface affinity and Multi-Queue. This will cause all SoftIRQ processing for all interfaces to happen on the lowest-numbered SND/IRQ core, typically CPU #0 which can easily get overloaded in this situation. After disabling SecureXL keep an eye on the RX-DRP counter reported by command netstat -ni, if the RX-DRP rate rises above 0.1% on any interface you will need to define manual interface affinity via the fw ctl affinity -i command and the fwaffinity.conf file (not the sim affinity command since SecureXL is disabled) to manually spread SoftIRQ processing around on the SND/IRQ cores. Disabling SecureXL and defining manual interface affinity is not a path I would recommend going down if it can be avoided.
Gateway Performance Optimization R81.20 Course
now available at maxpowerfirewalls.com