You can't do it with strictly HTML or PHP; you will need CSS and JavaScript (it's feasible with just JavaScript, but I recommend the CSS+JS route). I suppose it's possible to make it not process that until after and just insert the stuff by traversing the DOM or using innerHTML... but it depends what the contents are.
If it contains just text, just having the stuff in the script tag is "processing" it anyway, so the only way I can think to make it delay the processing is by using the PHP to store some sort of temporary file, then accessing that file with an XmlHttpRequest. Pretty undesirable. But if it's just text, unless it's an entire book, processing it on page load is probably not bad.