I have noticed that the wp_posts is very large/big. I have deleted all post revisions ans clean that table.
I have to blogs, with almost the same posts numbers with not so big content. On the first blog the wp_post is 18MB, but on the other wp_post, it is 71MB.
wp_post size: 19MB
wp_post size: 71MB (this is so big)
I guess it is not about revision, couse this is disabled e I have cleaned it.