Modulo the obvious mistake, the answer is probably, "It will do both."

Perl 6 aims to have multiple parsing front ends and multiple working back ends. The default back end that you get with perl will work as the current one does, interactively, and so cannot afford to be overly aggressive in optimization because compilation time is seen as part of run-time. However there are planned back-ends which will be able to take the time to optimize more aggressively.