When readers, including me, post comments to my blog, they don't show up for minutes...sometimes hours...although they are immediately visible in the admin panel.
If I go into Options > wp-cache in the admin panel and delete cache, then refresh the page, the delayed comments appear on the site.
Because of the high-volume of traffic my site receives, I need the wp-cache plugin. It's supposed to clear cache each time a new comment is posted, but it doesn't happen. (I get a lot of comments too).
You can test this at my site: http://www.ScrappleFace.com
Please alert me if you respond here.