Utilitarianism- Just too hard?

In our group we were asked to decipher about a page and a half of John Stuart Mill beginnig on page  “The objectors to utilitarianism… - manifestly pernicious to society” (326-327) What we’ve been able to come up with so far is that in the opening paragraph, the argument that the objector to Utilitarianism makes is that it is a standard that is”too high” for a human being to be able to uphold. The idea that a person must try to take into account everybody else’s feelings and overall pleasure in a split second before they do something would be too much to take. Better put, it’s inconceivable that a person would be able to analyze a situation instantly before they make any actions that could affect others (be it in a pleasurable or painful way). So far Mill has not responded to this claim, so stay tuned for some updates.