How to find out why Javascript is downloading so slowly?

Question

I have an ASP.NET MVC project, which is running as slow as molasses. I opened up Fiddler on one particular call, and found several calls where there's a lot of room for improvement, to say the least:

The blue lines I understand are calls to my controller, and I understand where to go to optimize that stuff. But I see a bunch of green lines (which I assume means javascript), and those are also taking a heckuva long time. I must assume that jQuery and Kendo scripts don't normally take 4-6 seconds to turn around, so there must be something in our project code that's causing the slowness. But how do I track down what code needs optimization?

EDIT: @DaggNabbit in comments below points out that the slowness is because these Javascripts are being called with a cachebuster parameter, so they're being downloaded anew with every call! But I can't see anywhere in my code where we're explicitly adding a cachebuster. e.g.:

<script src="@Url.Content("~/Scripts/kendo.web.min.js")"></script>
...
@Scripts.Render("~/bundles/jquery", "~/bundles/jquerymobile")

I'm really not a UI expert, but I can't see where the cachebuster is coming from. Any other ideas?

Answer 1

The problem that @DaggNabbit correctly identified is that the javascripts were being called using a cachebuster parameter. I've invited him to post his answer as the correct answer; when he does so I'll give him answer credit.

Meanwhile, if you're interested in why the cachebuster was being inserted, see here.