Nowadays the software renderer for WebGL works fine. I wonder if there is some easy way to detect if the video adapter is affected (probably intel && being "old") and if that's the case, to switch to software renderer, at run-time - maybe before initializing QApplication? in order to pass --enable-webgl-software-rendering parameter programmatically.

Here are the screenshots depicting the problem:

Hey, thanks for the info, I'll try that.

Just an FYI, disabling network adapters (used by virtual machines) in Device Manager solved the sluggishness for me.