I just finished the upgrade to das Blog 1.9.7174.0. This version has more support for reducing comment-spam. (See http://www.dasblog.info/ for other changes)
Browsing thru the old posts revealed a large number of 'contributions' from China and the Middle East. For some reason deleting comments from a post that has more than 4 comments takes quite some time. The amount of time increases exponentially with the number of comments. Not sure what causes this.
Luckily v1.9 allows me to prevent comments on posts older than 60 days, so cleaning old posts shouldn't be necessary after this.

One of the 'benefits' of removing comment spam is that it did demonstrate that Vista displays all of those non-western character sets. So we're one step closer in actually understanding what they are trying to sell.