Originally Posted by rdhw

Well, partly. The other factor is that, when you set an explicit proxy, you use only that proxy, for all your traffic. When you do not configure an explicit proxy, your traffic gets allocated to one of a local cluster of proxies, chosen on the basis of the requested HTTP address. If one proxy of the cluster is sick, you notice poor performance on all the addresses that it handles. When you configure an explicit proxy, you probably choose a different member of the cluster (one that is working normally). This is why it often appears that explicit use of a local proxy works when the default transparent does not. If you were to check out every member of the local cluster, you would probably find which one(s) were sick and which were fine.