I run a big site with a lot of activity and 150k+ registered members. I use this plugin and recently had to add someone to a list of members excluded from display in top 10.
Then I noticed that a MySQL query examines 150k+ rows each time it's used, completely massacring the database. I was wondering is developer of this plugin could fix it. It will not have an impact on sites with only a few members, but when you get into 6 digits, that's a significant strain on the processor:
# Time: 120703 3:20:01 # User@Host: @@@@@@@[########] @ localhost  # Query_time: 0.709128 Lock_time: 0.000086 Rows_sent: 10 Rows_examined: 153969 use %%%%%%%%%; SET timestamp=1341310801; SELECT COUNT(comment_ID) AS <code>comment_count</code>, comment_author, comment_author_email, comment_author_url FROM wp_comments WHERE comment_approved = 1 AND comment_type = '' AND LOWER(comment_author_email) NOT IN('firstname.lastname@example.org') GROUP BY comment_author_email ORDER BY comment_count DESC LIMIT 10;