今天碰巧发现 VPS 的 CPU 占用率达到60%，就检查了一下服务器，发现是因为国内一个 IP 在扫描网站上可能存在的压缩文件包（估计是那种寻找机会的无聊“黑客”）。顺便测试网站在国内的连通性的时候发现之前响应速度超快的网站居然变得很慢。
Recently, I have re-activated the WP Super Cache plugin to make my website responsing faster. But I notice that the post cache is not updated after editing. Further debugging shows the reason is that WP Super Cache does not deal with https related site properly.
With WP Super Cache 1.0, the author Donncha added a feature of preloading taxonomies (tags, categories) and custom post content. But if you run a multisite WordPress in sub-directory mode, this feature could be failure in the main blog.