Bug Unity WebGL poor rendering performance on iOS 16.x safari

We test a rendered scene without much computational logic. In iPhone13 (iOS 16.2) iPhoneX (16.3) safari, it can be seen that the frame rate is very low, only 12 fps. Demo: https://www.oooceanworld.com/testgame/rendercase1

After repeated attempts, the frame rate will be increased several times(fps12-->60!!) by disabling the WebGL on Metal option of safari.

1. Use safari to remote attach and look at the timeline, you can see that it takes 100ms+ from requestAnimationFrame request to actual execution (such as frame269)


2. Using the Instrument activity monitor, you can see that the usage of the GPU process is significantly higher, and it will be less than 5% when disabled WebGL via metal


3. Use the Instrument Metal System Trace tool to detect the GPU process, and you can see that the data between the two is very different. Enable WebGL on Metal

 

Looks like it has something to do with iOS "WebGL Via Metal", any info on that? @brendanduncan_u3d

 

That issue seems to be related to "too many uniforms". How to confirm what is the cause of my case? Is there any more accurate means of webkit analysis or workaround solution from the game logic?

 

@brendanduncan_u3d, The safari rendering of Unity games on iOS/macOS still has serious performance problems. When WebGL Via Metal is turned on and off, there is a clear gap. I submitted an issue to webkit, can you help me find the reason?

255987 – [ANGLE] Poor game render performence when enable "WebGL Via Metal" (webkit.org)

 

This is 10000% a massive issue. My game runs perfect on windows/chrome. Its absolutely garbage on macos and is a small game.

 

255987 – REGRESSION (iOS 15.4): Poor game render performance with "WebGL via Metal" (webkit.org)
@brendanduncan_u3d, From the development reply of Apple's webkit, this performance problem seems to be a bit complicated? It will involve several dependent issues

 

In our case the metal backend for webgl siltently crashes/restarts our application after a short time running. So I'm assuming the fixed bug mentioned above still didn't hit latest safari? I'm on ios 16.5