I need to monitor hall sensors for position encoding with up to 350 changes per second.

REFRESH_RATE = .0005

while True:
    new_p1_state = GPIO.input(hall_p1)
    new_p2_state = GPIO.input(hall_p2)

    if new_p1_state != p1_state or new_p2_state != p2_state:
        if p1_state == GPIO.HIGH:
            if new_p2_state == GPIO.HIGH:
                position -= 1
            else:
                position += 1
        else:
            if new_p2_state == GPIO.LOW:
                position -= 1
            else:
                position += 1

        p1_state = new_p1_state
        p2_state = new_p2_state

    time.sleep(REFRESH_RATE)