If your chat-message filter is more CPU-intensive than average, or does more with a message than just filter it, you don't want it running on spam when a faster spam-filtering add-on is present. You can post-hook ChatFrame_AddMessageEventFilter, but if multiple add-ons are doing that then it takes an exponentially-growing length of time.
That's where AddMessageEventFilterLast can help! It keeps the filter functions using it at the end of list.
Auctioneer statistics module that uses market data from WoWuction.
Auctioneer statistics module that uses market data from WoWuction.