It is known, that TeX algorithm to split long text into strings to make paragraph is globally-optimal, but splitting stack of lines into pages are only locally-

It is known, that TeX algorithm to split long text into strings to make paragraph is globally-optimal, but splitting stack of lines into pages are only locally-optimal due to memory constrains at the time of original TeX implementation. Does this system uses globally-optimal algorithm for second step (page composition)? Does anybody know globally-optimal formatting system?