Connections creation and management
Sometime overall network speed can be hampered by connections creation and management speed. While this is rarely a problem for home and small office, it can be the case when you have some high-load, high-access web servers behind you firewall and / or you are using some client software that use lots of connections (eg: Microsoft Outlook clients connecting to an Exchange server for push notifications or rich web-based applications).
For testing connections creation and management speed I used the trusted Apache Benchmark, with Apache itself showing the default CentOS test page:
While firewall-only rates are quite good, UTM-enabled ones suggest us to use this firewall for LANs with a maximum of 15 / 20 client machines. This does not means that you can not use this appliance for slightly larger networks, but sometimes you will have to wait a few more seconds to load your preferred web page.
So, what about web page loading latency?
Loading latency remain under control most of the time: in 95% of all cases, the test page was loaded between 6 ms (basic mode) and 26 ms (UTM + VPN mode). Moreover, while absolute maximum latency is greatly influenced by UTM and VPN functionalities, it remain under 700 ms (less than a second, if you prefer).