However, a simple queue isn't that great — firstly, if a method is, for some reason, taking a very long time to complete, running it over and over again whenever the client generates a request is **missing "a"** bad idea (potential for Denial of Service attacks), and, secondly, AJAX is often **"to" should not be here** used to provide a quick status update to the user, so continuing to run the action after a long time isn't useful. Two small errors indicated with enclosing ** It's also a really long sentence.
I have corrected this in the guide for the FP release and split the sentence into 3 sentences. 1st: "However, a simple queue isn't that great." 2nd: Starts with "Firsty" 3rd: Starts with "Secondly"