This began with my site being down with no errors present. I figured out that a table had crashed and was able to get my site back up.
Looking through the forum, I now have about 250,000 new discussions. Most SPAM users have about 5k posts each which is overwhelming the SPAM cleaner. Without having a week old DB to restore, what are my options here?
You could try the batch thread delete system in the control panel. It may be able to take them out in smaller batches (as the spam cleaner is designed to take out the content in one go, so increased thresholds may not work).