One of the University's five cache servers has developed an intermittent problem. When the problem surfaces, some (approximately a fifth) users will experience extremely slow response when they try and access web pages. We understand the cause of the problem and are working to resolve it.
For those who're interested, f.cache.ru.ac.za is running out of file descriptors. The machine will allow the cache process to use approximately 11K file descriptors but for some reason squid is only using 1024. We'll install a new version, with a higher file descriptor limit, as soon as we can. There's no point in turning f.cache off, because this will simply shift the problem to one of the other caches.