TBH (Not flaming here) The game does need optimisations but is will definitely work well with a GTX 1080Ti, a limiting factor could be your RAM or CPU if you are still experiencing framerate issues.
I use a GTX 1070 to run the game along with an i7 6700 Quad Core CPU and 8GB of DDR4 RAM and it runs at 60fps constant.
Also if I am not mistaken the GTX 1080Ti must have some internal VRAM in it which helps greatly with performance when gaming (The GTX 1070 has 8GB DDR4 VRAM) so have fun ;)