Pls note: BetterRepack and HF Patch aren´t compatible, as the description of BetterRepack says.
Your troubles with 1070 Ti are unusual for me, I only know messages with RTX30.. cards.
And my GTX 1660 Ti doesn´t know any performance issues......................
Did you place your game folder on top of the drive? Without any unnecessary subfolders?
BTW, 1660Ti is Turing, like RTX 2XXX generation, 1070Ti is Pascal, an older architecture. They're not similiar I'm afraid. 3XXX is Ampere.
It's sits in D:\Games\HS2 on an SSD M.2 drive.
I tried HF Patch on a BetterRepack only after not succeeding in optimising the game and it didn't affect it in any visible way.
I'm re-downloading BetterRepack R9b now to reinstall it altogether, but I don't assume that it can change anything.
I the meanwhile I've tried vanilla game (Steam release). It runs buttery smooth with constant 60 FPS (I capped it at 60 with MSI Afterburner / RivaTuner).
After applying HF Patch to the vanilla game, it got slow again. Not as slow as BetterRepack, but I didn't use any girls with next gen skin or custom clothing and that might be the case. Disabling shadows made it run a little smoother*, but it also looks weird without them. I think GraphicsMod is to blame, but IDK why does it work like that. This game shouldn't be that slow on my PC. And I'm not even playing my native resolution, 1440p, only 1080p.
*Edit: it depends on a map. In a "Female Room" my FPS goes from about 17-21 with shadows on to 40-50 without the shadows.