2010/5/25 Aryeh Gregor Simetrical+wikilist@gmail.com:
Templates will often miss the parser cache, because different invocations will use different parameters. Even *with* the parser cache, parsing is *still* one of the most expensive operations Wikimedia does, so I'm not so sanguine.
I wasn't talking about the templates themselves hitting the parser cache, but about the pages that use them. Of course the number of pages using interwiki transclusion over time plus the edit rate of those pages could grow to become a problem.
Also note that you wouldn't technically be parsing, just preprocessing on the home wiki, which is certain to be less expensive (how much less I don't know), and that you'd be doing this on some wiki anyway, so only the overhead involved in HTTP, the API and initializing the parser is relevant; the actual cost of the operation is not, because you're doing it someplace either way (of course this only applies intra-WMF, not to external clients).
Roan Kattouw (Catrope)