Why is web browsing through the Guardian web filter slow?

Article #: Product Castle
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An explanation of possible causes for a temporary slowness when browsing via the Guardian web filter.


Web browsing seems to be slow when using Guardian web filter.


DNS resolution

Check that Guardian can still resolve internet hostnames in a timely fashion. If DNS is the issue, the symptom will often be that accessing a web site 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 simple ping of a hostname on the command line will also give a general idea of how long it takes for Guardian to resolve a host and domain name. The ping time itself is not what is important (unless you find it is very slow).

Anti-Virus Scanning

It can give the impression of slowness as the Guardian will have to fully download all elements and scan them before passing them onto the client. AV scanning of graphics in particular can make Guardian seem slow.

System Load

Check system load — go to Network > Configuration > Interfaces. Each interface has its own traffic graph.

Check memory usage — use the Resource usage panel on the Dashboard shows the amount of memory and swap in use. If a large portion of swap is used, then the system may 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.

Bandwidth usage

Check bandwidth usage in general — bandwidth may be used by services other than Guardian, slowing down web browsing . Use the traffic analysis tool on the Smoothwall (Reports > Realtime > Traffic graphs) to determine current throughput.

Check cache size setting. Normally, we do not recommend cache size above 1.5 GB — if the size is set significantly higher, the system may use more resources managing the cache than managing the connections and filtering.


Last updated: Author: Contributions by:
30 August 2016   Tanja