Quote Originally Posted by pauland View Post

Then I thought about the iframe and it seems that that is the culprit here - they slow things down compared to rendering within one page, an iframe is really a web page within a page and takes a performance hit.
Thank you pauland!
That explains the iframe loading time. However, the T-shirt editor is loaded by iframe as well and loads straight away even though it is way bigger like you found out. (I think they are changing that to html5 soon)

Does anybody know of a different solution to an iframe? In any way, I don't think I will be able to fix this and the loading time seems to be okay in other countries so thank you all very much for your help!!!!