Mostly I can't test script, cause I do not know how to avisynth on any player expect PP, it seems to difficult and unusable to test it, anyway ffdshow even in x768 does not give improvements in perfomance in my case, I watch movies from laptop not very often, I need autocrop not very often too, etc). If it's not difficult, you can use this script/library
https://vk.com/doc275347426_499703245 , I add it.