Hi,
Sorry for the issues you are having with this. I can help troubleshoot it with you.
I visited your site and see what you mean. Although it does not happen with every browser.
I am not sure of the cause of this. It could be a server issue over a theme issue or a combination of both.
The only thing I can suggest is to run through our testing for conflicts guide:
Testing Conflicts With Themes and Other Plugins
That would help narrow down the source of the issue.
Let me know what you find out and especially if another theme is able to recreate the problem.
Thanks