ufdbGuard is the fastest URL filter available for Squid. It does 30,000 URL verifications/sec on a 2.8 GHz CPU.
ufdbGuard is free and based on SquidGuard. You can download it at the home of ufdbGuard and SourceForge.
A URL filter needs a list of URLs of undesired web content. Such a list is referred to as a URLFilterDatabase.
ufdbGuard is Free software, licensed under the GPL, but you must pay to have access to its database of URLS to block (and updates to the list).
4 pages link to ufdbGuard: