In the new patch of posts there isn't "b-loaded" class by default, even if it's the same avatar that was already loaded in previous patch. If first Ajax response is like <span class="b_lazy" data-src="/images/image1.jpg"></span> and second response is the same <span class="b_lazy" data-src="/images/image1.jpg"></span> then in the second response it will handle data-src, because there isn't loaded class yet. It may be that this is uncorrectable problem and we just have to live with this.