Problem with NodeMcu interrupt

Question

I am Using Arduino IDE to program NODEMCU. I am expecting LED should remain ON for 4 sec. But it turns OFF in less than 2 sec. Please can anyone explain me why this happening? Also I noticed that if serial monitor is used, led ON timming changes with baudrate. I don't know why this is happening.

#include <ESP8266WiFi.h>
#define LED D1    // external LED is connected to pin D2
uint8_t GPIO_pin = D2;
void ICACHE_RAM_ATTR IntCallback();

void setup(){
  pinMode(D1,OUTPUT);
  attachInterrupt(digitalPinToInterrupt(GPIO_pin),IntCallback,CHANGE);
}
void loop(){
  digitalWrite(LED,LOW);      // Turn off LED to indicated Interrupt routine ended
  delay(1000);               // Without this delay, LED just blinks too weakly for milliseconds
}

void ICACHE_RAM_ATTR IntCallback(){
 digitalWrite(LED,HIGH);  // Turn LED ON to indicate Interrupt Routine started
 delay(4000);             // Delay in order to keep LED ON
}