This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
I must admit, I didn't know what that was particularly getting at. But I just did a search of that site looking for other rereferences to see if they explained more what they meant. And found the equivalent page from the first edition (I think) - http://www.corej2eepatterns.com/Patterns/InterceptingFilter.htm - which goes into more detail:
Information Sharing is Inefficient Sharing information between filters can be inefficient, since by definition each filter is loosely coupled. If large amounts of information must be shared between filters, then this approach may prove to be costly.