ESP12 serveur web problème temps de chargement

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
//ajout neopixel
    #include <Adafruit_NeoPixel.h>
    #include "header.h"
    #include "footer.h"
    #define PIN            D3
    #define NUMPIXELS      106
    Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);
    bool oldState = HIGH;
    int showType = 0;
    int brithness = 25;
    int arc_ciel = 0;
    
//ajout neopixel FIN
const char* ssid = "";
const char* password = "";

ESP8266WebServer server(80);

const int led = 13;


void handleRoot() {
  
  String msg = HEADER_page;
  msg += brithness;
  msg += "\" ><input type=\"submit\"></form><h2>Couleur uni</h2><a href=\"?r=255&g=255&b=255\" class=\"img\" id=\"blanc\"></a><a href=\"?r=0&g=0&b=0\" class=\"img\" id=\"black\"></a><a href=\"?r=255&g=0&b=0\" class=\"img\" id=\"rouge\"></a><br><a href=\"?r=255&g=255&b=0\" class=\"img\" id=\"jaune\"></a><a href=\"?r=255&g=100&b=0\" class=\"img\" id=\"orange\"></a><a href=\"?r=255&g=0&b=255\" class=\"img\" id=\"violet\"></a><br><a href=\"?r=0&g=255&b=0\" class=\"img\" id=\"vert\"></a><a href=\"?r=0&g=0&b=255\" class=\"img\" id=\"bleu_royal\"></a><a href=\"?r=0&g=191&b=255\" class=\"img\" id=\"bleu_ciel\"></a><h2>Sénarios</h2><ul><li><a href=\"?fondu=1\">Couleurs fondu</a></li><li><a href=\"?ciel=1\">Arc-en-ciel</a></li><li><a href=\"?fr=1\">France</a></li><li><a href=\"?disco=1\">Disco !</a></li></ul></body></html>";
  server.send(200, "text/html", msg);
}

void handleNotFound() {
  digitalWrite(led, 1);
  String message = "File Not Found\n\n";
  message += "URI: ";
  message += server.uri();
  message += "\nMethod: ";
  message += (server.method() == HTTP_GET) ? "GET" : "POST";
  message += "\nArguments: ";
  message += server.args();
  message += "\n";
  for (uint8_t i = 0; i < server.args(); i++) {
    message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
  }
  server.send(404, "text/plain", message);
  digitalWrite(led, 0);
}

void setup(void) {
  pixels.begin();
  pixels.setBrightness(brithness);
  pixels.show();
  pinMode(led, OUTPUT);
  digitalWrite(led, 0);
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  if (MDNS.begin("esp8266")) {
    Serial.println("MDNS responder started");
  }

  

  server.on("/", []() {
   
    if(server.argName(0) == "r" && server.argName(1) == "g" && server.argName(2) == "b"){
          int r = server.arg("r").toInt();
          int g = server.arg("g").toInt();
          int b = server.arg("b").toInt();
        
          for(int i=0;i<NUMPIXELS;i++){
              pixels.setPixelColor(i, pixels.Color( r,g,b ));
              pixels.show();
           }
      }
      if(server.argName(0) == "puissance")
      {
        brithness = server.arg("puissance").toInt();
        pixels.setBrightness(brithness);
        pixels.show();
      }
      if(server.argName(0) == "ciel")
      {
        rainbowCycle(100);
      }
      if(server.argName(0) == "fondu")
      {
        arc_ciel = 1;
      }
      handleRoot();
  });

  server.onNotFound(handleNotFound);

  server.begin();
  Serial.println("HTTP server started");
  
}

void loop(void) {
  server.handleClient();
  if(arc_ciel == 1) rainbow(20);
}
void rainbow(uint8_t wait) {
  uint16_t i, j;

  for(j=0; j<256; j++) {
    for(i=0; i<pixels.numPixels(); i++) {
      pixels.setPixelColor(i, Wheel((i+j) & 255));
    }
    pixels.show();
    delay(wait);
  }
}
void rainbowCycle(uint8_t wait) {
  uint16_t i, j;

  for(j=0; j<256*5; j++) { // 5 cycles of all colors on wheel
    for(i=0; i< pixels.numPixels(); i++) {
      pixels.setPixelColor(i, Wheel(((i * 256 / pixels.numPixels()) + j) & 255));
    }
    pixels.show();
    delay(wait);
  }
}
uint32_t Wheel(byte WheelPos) {
  WheelPos = 255 - WheelPos;
  if(WheelPos < 85) {
    return pixels.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  }
  if(WheelPos < 170) {
    WheelPos -= 85;
    return pixels.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
  WheelPos -= 170;
  return pixels.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}