I have been using the last good versions and writing my own scripts by hand for a while now. Both performance and quality are far better now than i have ever been able to get through the official GUIs.
The last good versions i had backed up were:
[Download Link]
svpflow1.dll [v4.3.0.156] & svpflow2.dll [v4.3.0.160] - 32bit AviSynth;
svpflow1.dll [v4.3.0.156] & svpflow2.dll [v4.3.0.161] - 64bit AviSynth;
svpflow1_vs.dll [v4.3.0.156] & svpflow2_vs.dll [v4.3.0.161] - 64bit VapourSynth;
I'm not sure if 32bit build 161 was ever even released as i haven't been able to find a single direct reference to it anywhere on the internet, but i can say for sure it wasn't released at the same time as the rest.
I have been testing and building up carefully quality and performance optimized custom script templates for older computers for a while now. Separated them into Anime, Mixed & Live Content types & Light, Medium & Heavy tiers. I'm not yet done, but i could put those up on github along with my notes and link them here if there's interest; maybe get some feedback as well...