New loading screen animation causes the editor to freeze

[Calinou]

Material Maker version: https://github.com/RodZill4/material-maker/commit/adb7b0e2bafe8fd861e441e94655177bc3fac8f9 (with Godot 3.3.3)

OS/device including version: Fedora 34, GeForce GTX 1080 (NVIDIA 470.57.02)

Issue description: The loading screen animation causes the editor to run very slowly and eventually freeze while the scene is opened in the editor. Could this animation be paused while in the editor? This would also avoid causing fans to speed up for no good reason.

Steps to reproduce: Open the Material Maker project in the Godot editor.