One notable example is that zooming of the main tracks, and sometimes of the piano roll, causes intermittent audio glitches or crackles since NAudio also operates on the UI thread. There's room for optimization because right now a lot of unnecessary recalculating of clip sizes and locations is being done, making interference with audio even greater with a greater number of clips/tracks. I think the main grid (the line grid for the measures or time sections) is pretty optimal because it is being tiled instead of fully drawn, but things like waveforms and midi note graphics have to be handled separately if they are to be zoomed in a high quality manner.