Had an interesting thing happen in the V8 firmware's spam filter. There was a 25K message to me on the server. It was coming in at a rate of a very few bytes per minute. Not kilobytes - bytes. It too so long to come in that another message would interrupt and it would start again. It did not download for two days until I turned off the spam filter for a minute.

It was a news message from a computer magazine that had a lot of links to news and ads and other stuff in it.

I've seen that a lot actually, and it seems to also happen with random large files. I suspect that it scans a binary representation of the large files and discovers some known patterns, thus slowing it down.