Performance drop in comparison to raw C++ library

[SgtChrome]

I am using a Raspberri Pi 1 B+ with the adafruit hat and performance mod enabled. Running the text demo included with the original library I am getting about 130 to 230 Hz. Running a demo of the Rust Bindings never nets more than 44 Hz. What puzzles me is that the following performance relevant parameters don't meaningfully change the result:

• Drawing more or less pixels at a time
• led-slowdown-gpio 0 or 1
• using adafruit-hat or adafruit-hat-pwm
• compiling for debug/release

All these settings combined don't change the total Hz gained by more than 1 or 2 Hz. I am wondering if the lower Hz rate is due to overhead introduced by Rust or if I am making a mistake somewhere. Could somebody confirm that there is a difference in performance?