Question independent and composed flip

[Killboywes]

Hey guys,
Quick question about Independent Flip vs Composed Flip with Moonlight at 4K 144Hz.
Setup: RTX 4090 host → Moonlight (4K144, V-Sync on) → mini PC (780M) → HDMI 2.1 → 4K144 FreeSync TV. VRR is working (TV shows Hz changes).
I’m forced to run 2 displays in Windows because of an audio workaround (soundbar), otherwise I get huge delay.
If I disable the second display → I get Independent Flip
If I keep 2 displays active → I get Composed: Flip
With 1 display: ~20–24 ms latency, perfect 144 FPS in PresentMon
With 2 displays: ~24–27 ms latency, Display FPS fluctuates ~139–144, but still feels completely smooth and TV stays at 144Hz
What I’m trying to understand:
Does that lower Display FPS in PresentMon actually mean dropped frames, or just DWM micro-jitter while output is still effectively 144Hz?
Is the ~3 ms increase just DWM overhead, and basically negligible?
Does VRR still work properly in Composed Flip as long as nothing is on top of the window?
Are those small FPS fluctuations just frame pacing jitter instead of real drops?
And I assume no tearing because Composed Flip is always synced through DWM (even without VRR)?
Main question:
Is Composed Flip really that bad in practice? I’m only seeing ~3 ms extra latency and no visible issues at all.
Curious what you guys think

[daemonjax]

It's dwm overhead and basically negligible.

For me, composed flip is smoother in Dune Awakening for some reason -- i get it by disabling MPO. Weird, but whatever works. Composed flip is close enough to hardware composed independent flip that if there's a compelling reason to use composed flip then you're not giving up much -- provided you're not actually using an ingame overlay. if you are using an ingame overlay, then PROBABLY the performance difference would be more noticeable.