[TF2] Performance issues since Windows 11 October 2025 KB5066835 [5561605] Update

[BlackAppV]

For the past few weeks, I've been having a problem where the game starts to stutter/lag after I send in-game chat messages. The problem only occurs after a certain number of messages have been sent. When it happens, it feels like I'm playing at 20-30 FPS. Unfortunately, the problem isn't visible in a recording. It can only be fixed by restarting the game.

[BlackAppV]

Additional information that may be noticed:

When the problem occurs, the entire system/computer is affected and stutters (noticeable through mouse movement).

[wgetJane]

does it happen when you send a chat message through the console: say <message>

[BlackAppV]

does it happen when you send a chat message through the console: say <message>

I tested it and the problem will not accurs if you type 'say ' in console or bind messages. Also it's not a mod or custom hud problem (tested).

I captured it with my phone, like I said it's not possible to record it on pc. (https://youtu.be/4Hi63ZT377c | Problem started at 1:15 | At the end you can see the whole system is affected (mouse movement))

I play the game with 2560x1440 16:9 and startup options: -windowed -noborder -condebug -conclearlog -usercon -g15

My PC Specs: Windows 11 Version 10.0.26200 Build 26200 x64 Bit GPU: EVGA 10GB NVIDIA RTX 3080 CPU: AMD Ryzen 7 5800X RAM: 32GB (2x16GB) DDR4 Corsair 3600MHz Vengeance RGB PRO SL Mainboard: MSI B550 TOMAHAWK SSD: 1TB Kingston A2000 M.2 PCIe 3.0 x4 NVME (L 2200MB/s; S 2000MB/s) SSD(2): 2TB Kingston NV1 M.2 PCIe 3.0 x4 NVME (L 2100MB/s; S 1700MB/s) Cooler: be quiet! Dark Rock 4 Power: 850W MSI MPG A850GF + Gold

[wgetJane]

so it's because of the chat window, not chatting itself

do you think this was because of a recent update?

are you using an fps config (mastercomfig, etc)?

[BlackAppV]

so it's because of the chat window, not chatting itself

do you think this was because of a recent update?

are you using an fps config (mastercomfig, etc)?

I'm using mastercomfig but I have it since last week, also I tested without it and the problem is still there. Gonna try vanilla, delete everything and reinstall tf2.

[wgetJane]

@BlackAppV probably not necessary, but if you're gonna go through with that, then use this guide:

https://docs.comfig.app/latest/setup/clean_up/

make sure to backup your cfg and custom folders first

[BlackAppV]

@BlackAppV probably not necessary, but if you're gonna go through with that, then use this guide:

https://docs.comfig.app/latest/setup/clean_up/

make sure to backup your cfg and custom folders first

I did a backup from tf2 all good, I tested it after reinstalling tf2 and it's still happening im sure its a recent update, because all worked before Scream Fortress 2025 came out.

[BlackAppV]

Solution found: It was indeed the graphics driver. I installed and tested an older version, and the stuttering/lag problem didn't occur. Now I've reinstalled the latest version of the graphics driver, and the problem has resolved itself. Perhaps it was due to an installation error. But thank you @wgetJane for your help.

I will close this post when I am 100% sure that the problem is solved.

[bigkwii]

Still happening as of today. Note: mods such as TF2:GR don't have this issue

[BlackAppV]

I found out a Windows Update started the Performance Problem. (Windows 11 October 2025 KB5066835 [5561605]) NVIDIA released a hotfix but for me it's still not fixed try to use a older Driver Version before mid October.

[wgetJane]

Still happening as of today. Note: mods such as TF2:GR don't have this issue

that's interesting, can you check if the base tf2 sdk has the issue