Unexplained hang in Safari 6.1 and Safari 7

If you are using the The PassKit Portal in the latest release of Safari (Safari 7.0) you may experience page hanging. We have raised this Safari bug with Apple, and will keep you posted of progress. To avoid the page hanging, we recommend you use the latest production release of Safari (6.0.5 8536.30.1) or the latest version of Google Chrome.
If you find any of your pages hanging, or would like to help further escalate this Safari bug please file a bug report using the Apple Bug Reporter.
For a copy of our bug report
Here is a copy of our bug report:
There is a bug still present on Safari 6.1 (8537.59) and now Safari Version 7.0 (9537.59). After further investigation, the freeze occurs between the DOM Ready and Window Load events – regardless of whether any Javascript is being executed.
The issue seems to be CSS related, in particular the display:none property. Removing display:none selectors from the stylesheet seems to speed loading but does not completely fix the problem – removing the stylesheet completely results in instant loading.
The stylesheet is completely valid CSS3 and the page is responsive in Chrome, up to and including version 31.0.1608.0, Firefox 23.0.1 and IE 10.0.9200.
This is a sophisticated page with quite heavy CSS and JS – however, it is valid markup, CSS and JS and performs well on all other browsers – Safari should be no different.
It is also not just this site that is exhibiting issues. For example, the Amazon Web Services Management Console experiences hands and load times >45 seconds in the Safari versions above, while it loads in less than 10 in other browsers.