I have added spam protection added to comments. Instead of various CAPTCHA based solutions I ended up using simpler and maybe even less annoying math based spam protection. Math Comment Spam Protection asks the visitor making the comment to answer a simple math question. This is intended to prove that the visitor is a human being and not a spam robot. I think for average site use answering a simple math is easier than trying to figure out hard to read text from tiny picture.
The math used will be easy. Example of such question: Sum of 9 + 9 ? The correct answer for this is 18.
I am added this spam protection because the amount of comment spam pushing to this site has been in unbearable and uncontrollable level. Something had to be done. I tested few option and this seemed to be the best solution.
I have used very good Akismet spam filter, which has filtered the spam out very well, but when the incoming spam reaches tens of thousands of spam comments every day some spam gets though and it will cause considerable server load. It seems that the comment posting and spam filter is not very optimized in performance, and in last few days the huge incoming spam flood had made the site slow to use (especially the site management). After adding this new spam control measure, the situation seems to have come to normal immediately.