ET Problem

we dont use AC on gathers anymore

Placebo, or rather disable fullscreen optimizations, there is no difference in core gather servers or public, they run on the same software, only lua addons is what makes them different, might be that the gather servers are less resource bonded and therefore it feels like FPS lag. If you still have this issue contact me on Discord, I'll see what I can do for you.

You didn't specify your hardware (mobo, gfx, mouse, etc) nor o/s system info.
You didn't explain exactly if you have some lagometer issues or fps drop when problem occurs.
Any other device plugged-in (e.g. drawing tablets)?
What exactly word "sometimes" mean? Sometimes - by time to time or sometimes - during specific mouse movement speed?

I assume you use win7 or such:

1. Check if the problem persist on USB 2.0, as I assume you use USB 3.0 (also fast charge?).
https://superuser.com/questions/783623/should-i-plug-my-mouse-into-a-usb-3-0-port

2. Use specific CPU affinity for ET.exe application (e.g.: 2nd or 3rd out of 8 - rather not last two; do not select more than one)
You can use Windows Task Manager to achieve that,
- Press: CTRL+ALT+DEL
- Click on: Run Task Manager
- Tab Processes
- RMB on process et.exe (you have to run it first) and select Set Affinity...
- Select 2nd or 3rd one as mentioned above (only 1 of them)
This solution often causes even more lags/stutters so you need to reconnect to the server/vid_restart to make it work proper. Thats why recommend solution below which is also more handy.
Best software to automize this is Process Lasso:
- Get it from: https://bitsum.com
- Go to: Options / Default Process CPU Affinities
- in area: New Default CPU Affinity
- In field Process match enter value: et.exe
- then click: Add to list
Now every time your ETPro will automatically be run on desired affinity (ETPro supports only 1 affinity so don't use multi-affinities and not 0 as it's often occupied by system applications; just experiment with it)
This is most likely the case:
"If a mouse responds slowly, it is because something else is hogging the CPU to the detriment of the mouse driver."
https://superuser.com/questions/783623/should-i-plug-my-mouse-into-a-usb-3-0-port

3. If that won't help try:
https://fearless-assassins.com/files/file/1656-rinput/
If you cannot be arsed to run rinput every time and type et.exe then run et.exe application just create batch file:
ETPro(rinput).bat
Inside file (should be 2 lines total):
START %etroot%\ET.exe +set fs_game etpro +set com_hunkmegs 512 +set com_zonemegs 128 +set com_soundmegs 161 +set cl_punkbuster 0
START %rinputroot%\RInput.exe et.exe

4. If that won't help make sure in BIOS you have DISABLED EHCI

5. Make sure you have DISABLED xHCI

6. Never plug your mouse to Fast Charge USB slot (You can also DISBALE this in BIOS).

7. If you have nVidia drivers try to change 3D application settings:
- Threaded optimization: Off
- Vertical sync (v-sync): Off or Use the 3D application settings (then in-game r_swapInterval 0) or Fast (then in-game r_swapInterval 1)
- Power management mode: Prefer maximum performance
EDIT: in-game cvar r_swapInterval 1 enables vertical synchronisation - and this is also causing mouse lag (but permament mouse lag, not sometimes)

ADDED:
8. Try this setting to 1 if you have laggy inputs (eg. mouse):
r_finish "0" - sync every frame disable


If you are an user of WIN 10 you can check here some solutions:
https://windowsreport.com/mouse-lag-windows-10/

DISCLAIMER: Start from the beginning till problem gone (I assume 2nd point is the real cause) / That also sounds like it's a negative acceleration, what is your CPI (DPI) value? If high then it could be the neg accel - check 3rd point.

maybe windows update re-enabling some "cool" features u disabled recently =]
go thru windows settings/privacy/gaming/xbox etc disable all the trash
probably wont help :DdDddd

edit: i had similar stuff going 2 or 3 years back.. but to how i could describe what i saw happening was, player models would teleport abit towards the direction theyr going i would get like 1fps for a milisec and back to normal after 0.92347sec. the movement would feel very robotic at the time. Or if there was no player for example and im tracking a wall it would appear like tearing.https://www.google.com/search?q=tearing&client=firefox-b-d&channel=crow&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjPoZTji97iAhWMxIsKHVljAqQQ_AUIECgB&biw=1920&bih=966
other, newer games i would run with no problem what so ever :D

heb je toevallig een toestel met gsync?
Die zou ervoor moeten zorgen dat je fps goed blijft zelfs al speel je zware games maar dat geeft lag bij het spelen van ET.
Heb het zelf ook gehad, gsync afgezet in nvidia control panel en probleem was opgelost.

Well, sounds similar to what I had. Had it all throughout 2014/2015, felt like a good excuse to stop playing at the time. There are a few other players who had this issue, there are some journals about it. Mize, med1xza, etc.

My issue was that the fps would drop slightly for just a second or two which caused jerky mouse movement. Still not sure exactly what causes it. In med1xza's case it was a Windows update afaik.

Format C

have it since years, thought its normal lOl

had the same and it was teamspeak causing the problem. playing on pub was ok but when i joined gather mouse movement was shit. try joining gather server without ts.

I had it aswell with my old mx518 and win7 combination. Your fps isnt rly dropping visually right on your fps display? Try to use an other mouse and see if you have the same problem.

Some people have been having some mouse lag occasionally when getting chat messages in programs such as Steam or TeamSpeak on the background while playing ET. For Steam the solution would be close Steam... :D

For TeamSpeak, since you need it in-game, try changing the options of TS to minimize it to tray while in-game. That has fixed the issue for a few players at least.

If u have win10, try to install ET on another harddisk than the system.