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