Someone made a mod to fix the terrible frame rate. I used version .97 nosetup
The mod here:
{ODKAZ SMAZÁN}https://www.mediafire.com/folder/wuzp6y6c3g8qq/div2#ot1jy29q3jjsp

Just copy the files into the game folder. (in steamapps)

Here is the youtube video where I got the information and mod.
https://www.youtube.com/watch?v=tgVnAhDyLfU
I only installed the mod, didn't do anything else in that video and it solved my issue.