Slow down PWM from ~10 kHz to ~2.3 kHz
10 kHz is too fast for the 7135 current regulator which requires at least ~5-8 µs to provide full current. With 2.3 kHz the shortes pulse (PWM level 5) is ~9 µs. This results in higher efficiency and should still be fast enough to not show visible flicker. The downside is that this might cause audible humming.