This article details a few things that you can check when your users are experiencing a temporary slow connection when using the Smoothwall Filter.
Check that the Smoothwall Filter can still resolve internet host names in a timely fashion. If the DNS is the issue, the symptom will often be that accessing a website initially takes time, but once on a site, navigation within the site is quick. Whenever a new domain is accessed, the access is slow again. A ping of a host name on the command line will also give a general idea of how long it takes for the Smoothwall Filter to resolve a host and domain name. The ping time itself is not what is important (unless you find it is very slow).
Antivirus scanning can give the impression of slowness because the Smoothwall Filter has to fully download all the elements and scan them before passing them onto the client. Graphics in particular can make the Smoothwall Filter seem slow.
Check the system load. Each interface has its own traffic graph, see the help topic, Adding new interface connections.
Check the memory usage. See the Resource usage panel on the Dashboard. It shows the amount of memory and swap in use. If a large portion of swap is used, the system might be bogged down by lack of physical memory. It is quite normal to see a Linux based system use 90% memory or more; it is the amount of swap used that will show if the system is low on memory.
Check the bandwidth usage. In general, the bandwidth might be used by services other than the Smoothwall Filter, slowing down web browsing. Use the traffic analysis tool on the Smoothwall Filter reports to determine current throughput, see the help topic, Viewing real-time traffic graphs.
Check the cache size setting. Normally, we do not recommend cache size above 1.5 GB if the size is set significantly higher, the system might use more resources managing the cache than managing the connections and filtering.