My lfs did somekind of update few days ago and now its lagging all the time.
Every 4-7 seconds the screen freezes for a short time (maybe half a second or so) nothing has changed in my computer or network.

The game is now unplayable because of that.
Any suggestion how to fix that?

1. Cap your frame rate at 100 to see if it has any effect (related thread: https://www.lfs.net/forum/thread/107882)

2. Disable your antivirus as a test step and see if it has any impact on your issue. If that doesn't do anything,

3. Check if you are on the current version (E12).

4. If you are, revert back to a previous version (i.e. E7, E8) and see if the issue is present or not (just to confirm that it occurs only in E12).

5. Make a post on the LFS Test Patch E12 thread (https://www.lfs.net/forum/thread/106967) with as much as detail as possible.

Hmmm All I did that I dropped max fps to 120 ans its now working, can't be that easy to fix
But thanks for those great tips

It looks like throttling due to excessive CPU or GPU temperature. After limiting the number of FPS to 120, the GPU / CPU works with lower efficiency and does not overheat, so there is no "Laggin"

Quote from Lucas McFly :

It looks like throttling due to excessive CPU or GPU temperature. After limiting...

I had it limited 180fps for about an year with this computer and suddenly when opening the multiplayer menu it asked to choose server: usa, netherland... etc. After that it begun to lag and stopped when I changed that max fps.

You don't need more than 100fps, as lfs physics engine at the moment runs at 100Hz. However, it does make sense to cap fps to 120, if you have a 60Hz monitor. It's only going to give you a bit more smoothness, at a small computational cost. If you have a 120Hz or even higher refresh rate monitor, then I would recommend to use vsinc, to lock fps to whatever is display Hz, as that gives best smoothness, while not introducing significant enough wheel/controller input lag, compared to 60Hz where 16ms is too much lag.