Qt OpenGL poor window resizing experience.

[BloodWiing]

Hello,

I've recently started playing around with Qt and was working on animations. They didn't run smoothly, so I decided to switch over to OpenGL as the renderer. All was good until I tried to resize the window.

Googling did not help at all (probably because I don't know what terms to put in the search bar to find more fitting results).

Thought maybe this had something to do with me running a 32bit compiler. Tried x64 MSVC2019 and MinGW, still the same.

Opened up the "Qt Hello GL 2 Example", it's the exact same effect:
https://youtu.be/XOrXbjkHu0M
(Though YouTube isn't the best to show the stuttering, it's close enough)
The window itself runs at 60 FPS, but drops to about 10 when resizing.

Am I doing something wrong, is this just an OpenGL issue? I'm really confused.

Thank you for taking your time to read this.

EDIT: I've checked the GPU usage.
Spinning the Qt model around used about 10%
Resizing the window used about 15%

I also use Qt 5.15.2