Some direct performance comparisons, played Ultimate Apocalypse mod:
OG: https://d.uguu.se/aEHXoHlv.webm
New: https://o.uguu.se/GmslArXV.webm
It's an improvement. Not 10x, but an improvement, nonetheless.
And Definitive Edition had Anti-aliasing ON as well, which wasn't in the OG.