Lag / Desync with the latest commits

[PokiP]

I updated from June 19th to the latest as of July 21st. Everything looks okay until you play as client. You can see when going from 0 to sprinting there is a lot of obviously visible lag and jitter that was not there before. Suspect to do with the new direction dependant speed?

• I confirmed this by installing into a fresh third person template project just now. Same issue everything default
• It doesn't happen every time but at least 1 in 3 times when going from dead speed, holding shift, then holding W

[PokiP]

https://streamable.com/6b11dp

[Sixze]

Could you please reupload the video?

I tried to reproduce this issue, but lags usually only occur under very bad network conditions, but I am aware that the current implementation of direction-dependent movement speed is not ideal, so I added a setting to disable it in UAlsMovementSettings.

[PokiP]

Could you please reupload the video?

I tried to reproduce this issue, but lags usually only occur under very bad network conditions, but I am aware that the current implementation of direction-dependent movement speed is not ideal, so I added a setting to disable it in UAlsMovementSettings.

https://streamable.com/6b11dp

Yup, it was on 5.4.2 if that matters. Great about the switch!

[Sixze]

Still can't reproduce this issue, I can only get something like this under bad network conditions, which is actually expected to happen.

[PokiP]

Sadly still seeing this with the very latest commits/branch and UE 5.4.3

• Default install. Merge the config files. Build
• Switch to client instead of standalone. Keep emulation off
• From 0 speed. Hold shift and W at same time to see stutter

Happens every about 2 out of 3 sprints for me. I noticed the independant movement direction defaults off now too, tried it both ways.

[Sixze]

I did as you said, but still no luck. There shouldn't be any lags if you have network simulation turned off at all, so make sure it's really off and other actions, like rolling, work without lags.

[PokiP]

I've looked deeper and think I have found a reason I see it but you do not. My usual FPS is 120 and it caps at that in the editor window.

If I add fixed client fps to 60 here

Then the problem is completely gone. Even though my editor window still shows 120. Theres no lag on sprinting

[Sixze]

Fixed in 3d4d50291d1f7bc1fa4c8d2b1f6c0add0820319e.

In ALS, the change of velocity depends on acceleration, and acceleration depends on velocity, so there is a kind of loop that usually causes no problems except in this case.

The CV_Als_AccelerationAndDecelerationAndGroundFriction_Normal curve controls this dependency, but since there was constant interpolation between the acceleration for running and sprinting, for some unknown reason it caused the server to not be able to change the character's speed correctly, and so it pulled the client back thinking the client wasn't sprinting, causing lags.

Removing the constant interpolation seems to have fixed this issue, but I'm still not quite sure why it was causing problems on the server.