This is kinda implemented. A lot written here isn't really workable, because the bulk of Tempcode evaluation actually runs on shared functions that come from templates. We can't change/inline that, as it would use additional RAM in a very poor trade-off.

Never-the-less, many ideas from this are now implemented (mainly in the compilation stage, with added idea of automatically replacing some symbols with PHP operators) and it actually seems to have given a 15% performance gain. This is working well alongside other Tempcode optimisations, and as discussed, we are very effectively making it so that Composr architectural features either optimise away, or don't have any cost if chosen to be disabled.