Slowness when filtering at destination in a rule by address-group

[BigPalo]

Hi,

We are having slowness in a traffic when the destination in the security rule is a address-group. If we configure "any" in destination the session are fast. The traffic is 443 (web-browsing).

How PA can cause slowness in https if the destination is a address-group? any idea?

[BPry]

@BigPalo,

You wouldn't expect this at all. The address-group gets expanded in the firewalls running configuration to simply include all of the addresses in the group, so using an address-group is the same as just specifying the addresses themselves in the security rulebase entry. 

What I can see easily happening is that your address-group isn't accounting for all website resources. So when you attempt to load the website, the website is loading slower because it can't download some of its assets properly. The way to verify this would be through the developer tools menu in your browser, or by logging all denied traffic on the firewall and making sure you aren't denying traffic from a test endpoint when using an address-group. 

Outside of the developer tools and looking at sources, you can use Fiddler to gather all of the requirements as well. Regardless, you're almost surely blocking access to certain assets which is causing the site to load slowly when you attempt to use the address-group.