10 second TTFB on individual files

[dme102]

Please take a look at my test result: http://www.webpagetest.org/result/141004_Z4_FVN/

As you can see, there are four WordPress theme files that are taking over 10 seconds to load, which is making every page on the site take more than 12 seconds until "start render".

I have tried disabling W3 total cache and have also updated my theme to the latest version.

I am using Amazon Cloudfront as a CDN (which should have automatically been disabled when I disabled W3).

This only started happening a couple of days ago.

Any ideas what this could be and how to fix it? Thanks.