iOS 15.1 huge web-gl performance drop.

[drfrankius]

We have several games using web-gl rendering with Phaser v2.18.0 (but tried other versions). After updating devices to iOS 15.1 (maybe 15 as well) the frame rate on iOS went from 60 fps to about 20 on our iPhone 6s test device.

I found this thread for a similar issue on Phaser 3. https://phaser.discourse.group/t/ios-15-performance-drop/10369/2

[samme]

I think we just have to wait for https://bugs.webkit.org/show_bug.cgi?id=230749 to get resolved.