int LED=8;//Pin Led (Attiny44 pin 5 = Arduino pin 8 )
int BUTTON=3; //Pin Button (Attiny pin 10 = Arduino pin 3).
unsigned long previousMillis = 0;        // will store last time LED was updated
unsigned long interval = 100;          // interval at which to blink (milliseconds)
int previousButtonState=1;
int ButtonState=1;
int ledState = LOW;             // ledState used to set the LED

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED, OUTPUT);
  pinMode(BUTTON,INPUT);
  interval=100; 
}

// the loop function runs over and over again forever
void loop() {
  //Controller BUTTON
  ButtonState = digitalRead(BUTTON);
  // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
  if (ButtonState !=previousButtonState) {   
    previousButtonState=ButtonState;
    if(ButtonState==0){      
      if(interval>1){
        interval=interval/2;
      }else{
        interval=100;
      }
    }
  } 
  ///Controller LED 
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;
    // if the LED is off turn it on and vice-versa:
    if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }
    // set the LED with the ledState of the variable:
    digitalWrite(LED, ledState);
  }
}