Persistent Mouse/Keyboard Input Response Lag in Multiplayer Games

[AveSharia]

I'm 8 hours in, and fighting a reproducible bug with registering mouse and keyboard clicks, specifically in multiplayer games.

There are a lot of threads mentioning input lag, but it always seems to come with general connection woes and desync. I have none of that — just perfectly consistent input lag in every co-op match I've played, and zero of the single-player matches I've played.

The closest related thread I found under Report a Problem was this one by Alzrath on 1/21/25. He described it perfectly:

Originally posted by Alzrath:

...dropping orders if you select and attempt to issue the order too quickly.

For example:
[ol]

• I press 1 to select my first control group of units
  
• I press A to start the attack command selection
  
• I left-click the field in an attempt to confirm the attack move order[/ol]
  The attack command selection may not get registered, and so it's interpreted as you selecting the units then left-clicking the field to deselect them, wasting your inputs.

I would only add that "too quickly" here is doing a lot of work. I have to wait about 500ms between box-selecting units and issuing commands. The game runs great otherwise- events occur at game speed, huge fights have decent framerates, and my co-op partner isn't experiencing any of this input lag.

I can visually see the lag: If I box-select units, the command card at the bottom doesn't update for about that 500ms. So anything I do in the interim doesn't register.

I've tried what seems like every possible combination of visual settings, resolution, v-sync, NVIDIA Control Panel settings, etc. and nothing has gotten rid of the input lag in co-op. A list of other random efforts I've made to get rid of it include:

• Windowed/Borderless/Fullscreen modes
  
• Updating to the latest NVIDIA drivers
  
• Re-installing/Repairing the installation in Steam
  
• Swapping mice
  
• Disabling "Night Light" in Windows
  
• Disabling Windows display scaling
  
• Playing different heros (someone suggested this in another thread)
  
• Hosting the game, having my friend host the game
  
• Disabling all overlays
  
• Disabling Windows Defender

It's difficult for me to believe this is anything specific to my system and not a bug, because again, the game runs perfectly in single-player mode. I can't even issue commands fast enough to cause the issue in single player.

Here is a pastebin of my DxDiag[pastebin.com].

[Tyranid]

I've also been running into input lag in multiplayer. It'll take around a second before a movement registers, and it can be even worse when trying to issue commands after selecting units or buildings.

This is easily my biggest gripe with the game. The unresponsiveness makes everything feel sluggish and can be frustratingly punishing.