After W11 25H2 update i have low fps on desktop and microfrezes when going from a window to another

I updated W11 to 25H2 and immediately notice the issue:

Basically i was used to play two (sometimes even three) idle games at the same time while watching a video or tv series in another window.
Since the update the following happens:
- the desktop, the fluidity of other windows, even the cursor get the same fps of the game. I tried with another game (diablo 4) setting max fps in background to 8 and when i alt-tabbed every other stuff was going to 8 fps. happens the same with every game. So if the game goes at 30fps, everything else when i alt-tab goes to 30 as well etc etc. 
- when switching between a game to another, before it was smooth, no issues at all (i did this for YEARS). Now if i click on a window and then in another i get a microfreeze everytime, not only on the two games, but it freezes the whole pc, even the movie, the song and every other stuff. I can't play them both together anymore.

Using AI i tried to identify the problem, from drivers, to windows setting (like enable/disable game mode and other stuff) but nothing worked.

I need help to fix this because of course happens not only in games but in everything. If open photoshop it is laggy as well. Before the 25H2 everything was fine.

W11 home 25H2
5080
9800x3d
32gb ram
1000w psu
i use two displays: the main monitor and an old tv as a secondary screen.

everything updated