Frame-rate drops at game beginning on iOS safari?

Hi, when playing our games on iOS(iPhone7,8) safari, it seams FPS is very low. For example:
1. At the beginning, FPS is less than 20 and also some janks. When monitor in xcode instrument, corresponding webcontent process cpu ls high(nearly 150~200%).
2. if play a little longer(maybe 2 min or more), FPS recover to 40(CPU is around 60~80%).
The first minute is very import to players. If game performance is low and players feel your game is boiling theirs phone, they will be lost.

After some research, I guess it relates to webkit WebAssembly Compilation mechanism?
In order to launch quickly, webkit use LLint(baseline compiler), then AIR generated in the background. So I think the reason maybe:
1. LLint performance is bad
2. AIR generation eat-up too much CPU resource

Then, all about this is related to WASM CODE SIZE. Most of our game's uncompressed code size is nearly 30M and very hard to shrink by a large margin.

Or is there other reason? Thanks in advance.

 

I looked into it recently too. You can see it on smashkarts.io if you play on any iOS device (obviously it is easier to see on older devices). It will be slow for the first 30seconds or so.

Getting it to work on mobile WebGL was a challenge with a few different issues to overcome along the way. But this was the only issue we have not been able to solve. For me this is the biggest issue with Unity WebGL on mobile. Apart from this it runs really well and our % of players on mobile is growing.

I connected from iPhone to Unity profiler yesterday and could see nothing weird going on with the game that would cause these slowdowns. So hopefully @Ocean2021 is correct in his assumptions and it will help the team figure out a solution to the problem.

 

Hi jukka, when I refresh the browser again, it will not run faster. There is still a drop in frame rate at the beginning.

 

We also see the same drops

 

Same issue here - reloading does not help.

 

Hi @jukka_j should I now check 2021.2.0a16? I saw the version of Emscripten not changed(1.38.11). Can we use simd128 flags in Unity 2021.2?

 

Thank you very much for your reply and look forward to the official release of 2021.2。
We are researching the method of webassembly for code separation. For example, record all the functions required during the startup phase as the first code package content. Reduce the pressure on downloading and compiling caused by too large code package.

 

When testing in 2021.2, the following code seems to have no effect

Code (CSharp):

1.  PlayerSettings.WebGL.emscriptenArgs = "-s msimd128";
2. BuildOptions option = BuildOptions.None;          
3. BuildPipeline.BuildPlayer(GetScenePaths(), "webgl", BuildTarget.WebGL, option);

I grep 'simd' in Folder WebGL/il2cppOutput/cpp and find nothing. Is there something wrong with me？

 

Unity2021.2 can reduce the amount of code, but it is not enough. A game with a code package of 30M when uncompressed requires nearly 50 seconds of JIT optimization time on iPhone7. Unity 2021.2 is difficult to significantly reduce the code size. Later, we tried to do wasm subcontracting by ourselves, and the situation would get better.

 

Any update on this?

 

Bump, have similar problem on iOS 15 Safari, app loaded fast, but fps are very small, before was on 2020, but came on 2021.2 for texture compression

 

Bump! Encountered same issue, both on iOS and Android devices.
Tried 2020.3.17f1 (LTS) and 2021.2.1f1 versions.
My 2D game is pretty small, but still game starts at framerate ~20 and after 15-30 seconds (depending on device) rises to 60. Tried to turn off almost all scripts, disable all coroutines and minimize gameobject count on scene, but in result initial fps raised to 40 recovering to 60 after same 15-30 seconds.

 

Bump using 2022.1.0b3 and I have found the same result. 30MB uncompressed file loads fine on Desktop, Android but on iPad I have 50 seconds of low framerates then it's fine. Wondering if there was any workaround anybody has found.

 

Hi, We are suffering from this issue too. It takes around 2 minutes on an iPhone X, to reach 60fps on our game. The uncompressed wasm code is around 34 MB in our case. Has anyone find any solution to this problem?

 

any updates?