During the verify process, you may see that after a minute or so, progress slows to a crawl, then after another minute or so, speeds up again. This usually indicates that something in your internet connection has begun dropping connections. BookMacster, and Bookdog 5.3.6 or later, detect when too many connections are being dropped, and respond by slowing the request rate until the problem clears, which usually takes another minute or so.
We did not see such dropped connections when the Verify function was originally tested in Bookdog back in 2005. It is possible that internet service providers have recently begun to recognize rapid visiting of websites as some kind of traffic that they don't like, and have set a policy to respond by dropping connections for a minute or so. When we get time to study this further we may post more information here. It would be interesting to see how this behavior varies among internet service providers.
For now, the algorithm used in BookMacster and Bookdog 5.3.6+ has been designed to squeeze as much as speed and accuracy as possible under the circumstances. Note that bookmarks which indicate a dropped connection on the first pass are retested on a second pass, which is likely to work since the request rate is much slower.