When clicking the button for publishing a new comment it takes a good 5-7 seconds before comment is submitted. For that period of time Apache takes 95 to 100% of the CPU of my VPS. When the page reload and the comment appears everything is back to normal.
MySQL works fine. Monitoring for queries slower than 3 secs reports no error. Apache error logs report nothing. Akismet queue is empty or with 100 spams only. Other operations on the website [admin/reader] are very fast. Using Ajax Comments doesn't help. Wusing WP-Cache2 doesn't help.
Any ideas? regards