Egon, could you possibly add that to version 1.33? I'm trying to mergeAll without looping but the line Object3D.mergeAll((Object3D[])new SimpleGlbLoader().loadGlbNoSkin(modelFile).toArray()) doesn't work. If I have to loop, we're back to very slow merging.
This should work:
Object3D.mergeAll(new SimpleGlbLoader().loadGlbNoSkin(modelFile).toArray(new Object3D[1]))