Weird results with latest Chrome version

I’m seeing a large performance parity between two different chrome versions. This is the problematic result:

The browser sits there using CPU without doing anything, before downloading a JS file. Latest Chrome in Phoenix, AZ USA, Windows 7, according to the headers.

And this is the result from a different location, which loads correctly. Chrome 40.0.2214.93.

I don’t think so as Firefox and IE from Phoenix, AZ USA both work fine. This page loads fine on our test machine running Win7 latest Chrome. How can I run a JS profile to work out what is happening in this 30 second gap?