No vsync slower than vsync every frame?

For some reason when I switch to lower quaity levels my game runs slower (from approx 60fps to approx 35fps). I experimented and it's definitely the vsync setting. I thought that no vsync was meant to run the fastest because it doesn't wait at all. Or could this be because I was running it in the Unity Editor?

Thanks in advance,
JT

 

Correct. No vsync will always run at least as fast as vsync, if all other settings are the same.

--Eric

 

Okay, thanks for confirming my thoughts. So the question is... why is it in practice slower for me with no vsync? Both the editor framerate and custom measured framerate confirm it. Are there perhaps other settings which are ignored or used differently depending upon the vsync setting?

 

Perhaps your fps measurement tool is simply broken? There is no possibility of anything being slower just because vsync is off. Perhaps you're spawning things and aren't using a very good timer, so when vsync is off, it spawns more than it can handle?

Regardless, fairly sure the problem is your own code.

 

Are you 100% sure that's the only difference? Don't change quality settings, just toggle vsync.

--Eric

 

or toggle it on / off in code:

QualitySettings.vSyncCount = 0; //or 1

 

That is literally the only difference. I changed the vsync setting in the editor while the game was running, back and forth a few times. Even with the game paused so the majority of things don't run.

One thing I do find strange is that when vsync is set to every frame the reported framerate (by both Unity and my custom code) can go higher than the monitor refresh rate. That sounds wrong to me...

 

That's the opposite of what happens with vsync.

--Eric

 

Possibly you have custom driver settings?

 

I totally agree, but that's what I'm seeing. I think firstly I'll test it on a build... the Unity Editor does weird things to performance sometimes. If that doesn't work I'll look into the driver settings.

 

Do you perhaps have a lot of code running in an update function? when the vsync is off, the update function will, if I understand it right, run as often as possible, which may use more CPU resources, and perhaps drown out some other parts of the system? Try putting all code in fixedupdate and see if it changes?

 

Same issue here. The problem happens on multiple computers, and both within the editor and with builds.
I made you a screenshot which shows the difference in the Profiler between v-sync (red, fast) and no v-sync (cyan, slow), switched manually. It seems that in the slow "Don't sync" mode, The CPU spends most of the time (about 0.18 sec per frame!) in "WaitForTargetFPS".

 

Note: I force Unity to use DirectX 12 (otherwise the editor slows sometimes down to about 4 fps). I've the impression that the v-sync bug doesn't appear in DirectX 11, but it's hard to test with my editor problems.

 

Do you by chance have a reference to Application.targetFrameRate in your code? When vsync is on this is ignored, but it wouldn't be with vsync off. It's hard to believe you'd have this in your code, but it's the only thing I can personally think of that would cause it to run slower with vsync off.

 

* Note: English translated into Google
I also encountered this problem and could not understand it.
So I tried and found the cause for several hours.

The cause was in Application.targetFrameRate.
If VSync is on, its value is ignored.
If VSync is off, it affects the frame.
The default value is -1, which works differently depending on the platform.
It seems that there is no limit on the PC.
But on mobile, it works at 30 fps.
So, when you turn off VSync on mobile, it happens to be slow.

Add the following sources.
Application.targetFrameRate = 60;

 

I too have this problem. If I turn off only vsync the player movement slows down but using "Every V Blank" option makes it run normally and using "Every Second V Blank" makes it run even faster.
I tried @imaginaryhuman solution about moving code from Update to FixedUpdate and it solved but I want to know why it slowed when using update + no vsync and not when using FixedUpdate + "any vsync setting"

 

That just means you made your movement framerate-dependent. Fix your code, don't put it in FixedUpdate (which is only for physics).

--Eric