AoE4, same like CoH2, has absolute performancetanking when it comes to the menu in a long session.
After every single game I personally can notice how the FPS drop and drop in menu animations, to a point in which it’s just a slideshow after 5-6 games/profile checks.
You can replace the webms for the background, similar to CoH2, but in this game it DOES NOT FIX THE ISSUE.
Go to:
C:\Program Files (x86)\Steam\steamapps\common\Age of Empires IV\cardinal\movies\source\fe\backgrounds
Create a new file and move the .webm’s into it.
Your menu background is now dark but the issue is fixed.
For those that like to mod around, you can enter your own webm’s as backgrounds as long as name and probably resolution of those match the originals.
Hope they fix the issue with the menu FPS drops.
Best regards.