After installing Attila, the .txt we need (preferences.script) should be located as follows;
C:\Users\*Yourname*\AppData\Roaming\The Creative Assembly\Attila\scripts

Once this has been done, open the file and locate two parts of this;
"number_of_threads" and "gfx_video_memory"

Threads needs to be set to how many threads your processor has (typically 8 should be enough however I personally set it to 15 (as I have a powerful processor) you can check by going into the details tab of task manager, right clicking an app (such as Attila) and set affinity (make sure you count CPU 0 as well unlike me).

Gfx video memory needs to be set to -4000. It's assumed that Attila wrongly calculates how much vram or rather caps the amount your card has which results in poor performance (alongside the other thread change). Changing this to -4000 causes it to detect more vram. Do not be alarmed if you load in and it says you have 512mb (that happened to me and I have 24gb), run the game and see the performance increase.