In my PHP class, the professor is asserting that the overhead for dropping out of PHP and back into HTML starts to stack up over many iterations of a loop. I said that I didn't find that likely, that it was sensible for the interpreter to break it down into essentially equivalent operations as it parses the file the first time. Unfortunately I can't find any actual data on this, likely due to a lack of decent search terms. So I turn to the Experts, that is to say, you guys. What do you think?