I have discovered a serious issue that I believe is caused by DisplayFusion, and it affects my gaming performance.

The FPS drop occurs in all Unreal Engine 5 games (Fortnite, The Finals) and sometimes in CS2, when I minimize (Alt+Tab) and then return to the game.

If I do this many times (minimize and restore), the FPS becomes terrible when moving the mouse — highly stuttering.

Interestingly, if I keep a mouse button pressed and move the mouse, the issue disappears (movement becomes smooth).

This behavior occurs both when the Alt+Tab function in DisplayFusion is disabled and enabled.

Restarting Windows Explorer sometimes helps temporarily.

If I completely close DisplayFusion, the problem disappears entirely.

Recently I also experienced a case where Alt+Tab did not work properly (the game would not switch or lose focus). I have reported this issue before.

Another observation: setting the mouse polling rate to 125 Hz partially mitigates the issue (but the problem still exists over time). At 1000 Hz, the lag is immediately noticeable.

I have recorded a video that clearly shows exactly how things happen. I struggled for years to identify the cause, and now I believe I’ve found the culprit

I noticed the same behavior. While gaming after alt+tabbing a few times the game would start to stutter and frame drop coinciding with mouse movement.

The fix for me was to add the game to compatibility and select 'treat this as a fullscreen application always'

Instant fix, I didn't need to restart the game, DisplayFusion, or windows.
Display Fusion Pro 11.1.1
Windows 11 (24H2) [26100.6584]
Star Citizen 4.3.1 LIVE

Unfortunately this did not help me, the problem still remains

Do you mean Beta 7?

I recorded a video where I encountered three bugs at once:

1. FPS Drop — the drop in performance when minimizing/restoring the game continues; this issue has not been fixed.

2. Alt+Tab broken / flickering — after launching Steam, Alt+Tab inside the game stopped working. I tried both tapping Alt+Tab and holding it down, but it just flickered (you can see it in the video). I don’t know exactly when or how it fails, but at first Alt+Tab worked in the game, then after launching Steam it broke.

3. Tiny windows in the Alt+Tab menu — the previews of open applications become very small or distorted in the Alt+Tab view.