Thanks. Well, this does make me wonder if we are doing something wrong or we are performing actions that are slowing down the crawling. We have a good server (I believe).
You might want to benchmark where your software is spending its time. A typical overhead is in the connection time. You may be able to speed things up with a local dns cache and by using http keep-alive. You also generally want to do a lot of parallel requests, since most time would be spent waiting for the subject site to respond.