xolox never released the source code so any true updates were never possible. all that was really possible was making it work after december 2001 as that didnt involve a change in line size in the program. as no1 could access the source code there was nothing else that could be done - if you've read some of the threads on here and at xenomorph's site you will realise that people have tried and if it had been managed it would have been widespread news.
i'm not sure how the version you have manages to cut down CPU usage as the code should be the same - infact the reason that it is so small is because it isnt the whole program - it is only a patch. i have another v1.13 which is even smaller. i cant really tell you much more - thats about as far as my knowledge goes but xenomorph may have more information for you if you want it - thats his field.
http://xenomorph.net/forum/
however, i agree with you about one thing, beta v1.18 is brilliant. if you liked v1.12 then you will love v1.18