jquery - How to find out why Javascript is downloading so slowly? -

i have asp.net mvc project, running slow molasses. opened fiddler on 1 particular call, , found several calls there's lot of room improvement, least:

the blue lines understand calls controller, , understand go optimize stuff. see bunch of green lines (which assume means javascript), , taking heckuva long time. must assume jquery , kendo scripts don't take 4-6 seconds turn around, there must in our project code that's causing slowness. how track down code needs optimization?

edit: @daggnabbit in comments below points out slowness because these javascripts being called cachebuster parameter, they're being downloaded anew every call! can't see anywhere in code we're explicitly adding cachebuster. e.g.:

<script src="@url.content("~/scripts/kendo.web.min.js")"></script> ... @scripts.render("~/bundles/jquery", "~/bundles/jquerymobile") 

i'm not ui expert, can't see cachebuster coming from. other ideas?

for increase performance can use javascript closure , css closure these responsable binding .js files 1 file , css files antoher single file increase loading time.