I switched this optimisation off back in
ed35d91be6, in October 2013, as part of a
big refactoring of the parsing and widget mechanism. I’ve been meaning
to switch it back on for some time.
My rough measurements suggest that this optimisation can reduce
rendering time by 5-10%.
There are still some warnings about making functions in a loop, but
I’ll fix those as a separate pull request because the fixes are more
than typographic errors.
This is a half-way through a big refactoring of the parsing and
rendering infrastructure. The main change is to separate the parse and
render trees, which makes the code a lot cleaner. The new parser isn't
yet functional enough to replace the existing parser so for the moment
you have to manually invoke it with `$tw.testNewParser()` in your
browser console. I really ought to use branches for this kind of
thing...
