I need a bit deeper explaination

[∴ ＣＺリＣＺ Ⲷ Ｋ ∵]

I've been using it for a while and it works fantastic. From 100 fps in doom eternal to 200 or even games that are capped like genshin just press the button and boom from 60 to 240 but this made me thinking a bit.

When using it, steam still sees the game as it plays in 100, so it doesn't effect game at all?
What I mean is that some games are locked at 60 because physics are programmed for 60. Because steam still sees it as original fps does it mean that this app is just some sort of "filter" that doesn't change game's properties or it's physics? Also some games that are capped (like genshin), do not allow third party programs to mess with games so is this safe to use in multiplayer and genshinlike games?

I also noticed that when using it, my browser (on second monitor) starts to stutter even though task manager says that usage is about 70% for both gpu and cpu so what is causing it?

[InvinGatoR]

"...it doesn't effect game at all ?"
Technically, it only effect GPU and CPU usage which depends on the hardware specification, could affect in-game performance.

"...this app is just some sort of "filter" that doesn't change game's properties or it's physics ?"
'Overlay' would be the correct word for this situation, and yeah it doesn't change the game properties or it's physics. Hell, it doesn't even touch any of the game folder / file at all.

"...is this safe to use in multiplayer and genshinlike games ?"
It is a safe program since it doesn't modify any file / configuration of the game and only intercept frames on surface window level, hence it need the application to run on border-less windowed instead of full-screen exclusive.

"...my browser (on second monitor) starts to stutter..."
Maybe try to toggling Multi-Display mode on Behavior. Idk about this since I never run or even had any multi-monitor setup.

[Rogen]

It basically creates an overlay running at a rate times whatever you've set the X as.

Let's say your game is locked @ 30 fps and an x2 is applied, the game itself is still running at 30 fps however the LS overlay window will run @ 60 fps e.g. twice 30 (X2).

And if vsync'd to a 60 hz monitor mode it will be super smooth.

A thing to be aware of is that your game can actually always achieve the 30 fps, else the x2 multiplier willl drop in step in keeping with the actual game frame rate.

The same rules apply for higher monitor sync and fps rates.

Cheers