Almost 20 seconds elapsed from the instant when you click apply to the instant you get back to Firewall rule page?
Guys, I hope that you track this as a bug and improve the performance.
I know this doesn't add any further to your request but the system load of almost 100 percent per core is unsustainable in a production firewall. I was running system load over 3 on my test firewall in a vm with quad cores. Yes throwing newer, faster hardware will bring it down a little but the system load has increased significantly in v18 compared to v17 and my test lab had only one user mostly playing with the GUI.
Attached is the load of my test virtual appliance. The load values are not significantly different from the originally used vmware virtual appliance v17.5. Vmware appliance is licensed to 4C6. Appliance runs on ESXi v6.7 U3, Intel (R) Xeon (R) CPU 5120 CPU @ 2.30GHz, RAM 2666GHz, and SAS HDD drive 10k with RAID6.However, I have found in the recent past that even with the new installation of ESXi hypervisor v6.7 the hypervisor installer installs very old network card drivers (especially for intel i350), it can be said very "antediluvian" and it is necessary to install the latest drivers using vmware CLI. Throughput is much better after installing current drivers on both network and storage iSCSI layers.
Maybe this could be the problem with your appliance's poor performance? I don't know what kind of environment you use, I just mention my experience.
focus on the topic of the thread.
If you have poor performance, open another thread. If you have complaint regarding the firewall or any other UI where too much time elapses from the time you click and the time you get back the UI, post here.