Bad performance when playing in Safari

Unity: WebGL

WebGL

2022.2.X

2022.1.X

2021.2.X

2020.3.X

2019.4.X

Canceling port for Unity 2022.1 as that product is reaching its end of support.

Unity 2019 is no longer accepting changes. Canceling port.

Reproduction steps:
1. Open the user's attached project
2. Build and Run for WebGL

Expected result: High framerate (60+ FPS) in Player
Actual result: Low framerate (~20 FPS) in Player

Reproducible with: 7.7.1 (2019.4.37f1), 10.8.1 (2020.3.31f1), 12.1.6 (2021.2.17f1), 13.1.7 (2022.1.0b13), 14.0.1 (2022.2.0a8)

Notes: - Safari gets ~20 FPS while Chrome gets 60 FPS - Using Unlit Shader gets 60 FPS on Safari