I wrote:
[...] Personally, whatever programming language would be chosen, I really like Aryeh's approach to sanitize and "compile" the template to PHP. It could be used everywhere MediaWiki runs, it is no hassle to set up compared to installing other in- terpreters and the performance should be the top of what PHP has to offer (and *all* templates could be compiled to that code). From a distance, I think it would even be easier to have the file/memory/CPU restrictions hacked into the main PHP interpreter rather than to cook our own soup.
Come to think of it, it would also fit very well with pro- filing individual templates.
Tim