Extra input delay for non-Steam games launched through Steam

[BlazeHedgehog]

Hi! Big proponent of launching everything through Steam. Including emulators! Most recently I have discovered that two emulators in particular seem to be suffering input latency issues with the current Steam Client. I don't think this is a result of the Steam Deck Big Picture update, but I'm not for certain.

The first emulator is ReDream. I am up to date with the current version of the emulator. In this case, I went from playing a different Dreamcast emulator outside of Steam (Flycast) to trying ReDream launched from Steam, and there is definitely a small, barely-perceptible delay in pushing a button on my controller and having the emulator respond. Launching ReDream on its own, outside of Steam, confirms that the delay goes away.

Now, I'd be ready to believe I am crazy on this one, that maybe it's a placebo, or anecdotal, or whatever, because this is just going by "feel." I think I feel input latency.

But the real hard evidence came just now when I downloaded the latest nightly of PCSX2 (1.7.3584). Launching that through Steam, I discovered that not only was there a perceptible amount of input latency, but the emulator even straight up drops my inputs entirely. For reference, I was trying to play the original PS2 version of Klonoa 2, since once upon a time, that was a difficult game to emulate accurately, and I wanted to test things. Unfortunately, if PCSX2 is launched through Steam, just doing basic actions like jumping seem to be a roll of the dice, as sometimes the buttons don't respond at all.

And yet again, just like with ReDream, if I launch PCSX2 on its own, outside of Steam, the input problems go away.

What's odd to me is this doesn't seem to effect all of my Steam library. I use the non-Steam version of RetroArch, but still launch it through Steam, and as far as I can tell, there's no input latency there.

System: Windows 10 Pro (19044)
Controller: Playstation Dualshock 4 (first version, without the enhanced light bar)

[BlazeHedgehog]

Also, I should note, every native, bought-and-played-through-Steam game does not seem to have any input latency that I've been able to detect.