Hi there I have made a fix for this game because i couldnt play it. I have uploaded it to Nexus Mods but because it is an executable file it gets flagged even if its a ZIP file... Sad but I am waiting for Nexus to reply. In the meantime I can confirm I have fixed the following issues for me. Lag, stutter, FPS drops during and after set pieces, kick off or just pausing and unpausing the game.
If you like you can download it for free here:
https://peterblack8.gumroad.com/l/iiaxun
I was just like you a day ago and didn't want to even bother but this has changed the whole game for me and I hope it does for you too!
Let me know if it doesn't because there are some other tweaks in windows that can have a huge impact on smoothness and fps dropping in games.