To maintain compatibility with old hardware, Drum Leveler supports OpenGL and non-OpenGL. If Drum Leveler's graphics are sluggish, please try experimenting with and without OpenGL.
In order to enable OpenGL:
1. Click on the Settings Icons.
2. Check the Open GL Graphics.
3. Close the UI and re-open. it.
* To disable OpenGL you can do the same but un-tick the Open GL Graphics.