Alternatives to Servo Library - ESC constrolling with Arduino YUN

Hi, I'm programming the autopilot for my quadcopter based on Arduino Yun. I'm currently writing to the ESCs using the Servo Library and I'm facing an annoying issue.

In Servo.h I changed the REFRESH_INTERVAL to 8000 (8ms periods) in order to write PWM signals at 125Hz . but I can't get lower . I can't either decrease SERVOS_PER_TIMER, or it won't work.

#define Servo_VERSION           2     // software version of this library

#define MIN_PULSE_WIDTH      544     // the shortest pulse sent to a servo  
#define MAX_PULSE_WIDTH      2400     // the longest pulse sent to a servo 
#define DEFAULT_PULSE_WIDTH  1500     // default pulse width when servo is attached
#define REFRESH_INTERVAL     8000     // minumim time to refresh servos in microseconds 125Hz
#define SERVOS_PER_TIMER       12     // the maximum number of servos controlled by one timer

How can I get a 4ms periods? Do I need to change library?? Arduino Yun and Leonardo have the same 32u4 microcontroller and timers work differently from the Arduino Uno.

Thank you

no one had the same problem?

What is the minimum time your ESC requires between command pulses?

It's suggested to have 250Hz - 400Hz PWM signal but I can't handle such high frequencies with Servo library