That is my experience too. when IH first scales the images there can be a delay. Evidently this is most noticeable when it is scaling pages with lots of new images. this really only happens onprodut listing lages after install. another thing that is worth noting is that different browsers deal with the delay in slightly different ways.

i am not sure about magicbox. You presumably want it to work on the main lroduct image. i do know that jqzoom plays nice with IH and there is a thread in which i am beinb persuaded to turn some code snippets into a proper module. search and you will find it