Just made some changes , check Discussions section. Ty.

Mods removed from the list due to bad mechanics, incompatibility and as such making the campaign extrem. easy even on Legendari diff and heaving Iron Man challenge on Hard - On :

1) Tycherious' MK1212 AD Overhaul
2) Diplomacy
3) Realistic Charge Impacts - not compatible with existing Realistic Cavalry Overhaul for 1212

Im not crashing at all been in mid game for while now and heaving large battles of 4 armies present on the battlefield and I have 1080Ti and Intel i7 9700k 16gb ram.
Try to do clean instalation of Attila, then start new camp. with only 1212AD then you exit the game and start turning mods one by one ( turn on one start new camp. then exit , reapit this process couple of times until you have mybe like 2-3 overhaul mods on ) It will work 100%

Also Im made UPDATE on compilation list cuz I tested and removed some mods that are,
trash they make the game very easy even on Legendary so make sure you also remove those mods, just look the updated compilation list.

Unfortunately, the game crashes during battle. All mods placed in the correct order. :(
Video card: AMD RX 6900 XT