Judging by the itwikisource jobs I just killed on most of the job runners, the parse time went up by a factor of infinity, not a factor of 8. They had been running for 3.5 days with --maxtime=300.
This surprises me. First of all, because a copy of Pagina Principale (with all it's transclusions) took ~30s to render on test2 (compared to 0.2s now). Secondly, because I would think that 3.5 days ago, itwikisource was already back on wmf4.
So don't do that. I find it hard to believe that allowing such a
feature will be an amazing win for the wiki's usability.
I constructed the most basic example I could think of. An example would be a template containing something like this:
==={{{1}}}=== {{#tag:section|begin={{{1}}}}}
In addition, see the relevant bugzilla thread: https://bugzilla.wikimedia.org/show_bug.cgi?id=21339
Double-parsing will break the syntax, {{!}} etc. will not work.
I'm not quite sure why this would be the case, but I'll take a look.
Merlijn