user42776: I have simple example, where in loop is called webServer to handle clients and also text drawing on display.
The thing is that webServer is not responding, but when I remove second part of loop - drawing text to display then web server starts to work normally. 
Server does not respond:

 void loop() {
      server.handleClient();
      unsigned long timeNow = millis();
      if ((timeNow > screenChangeTime))  {
          display.clear();
          display.setFont(ArialMT_Plain_16);
          display.setTextAlignment(TEXT_ALIGN_CENTER);
           display.drawString(12, 20,"Loaded: "+String(particles));
           screenChangeTime= timeNow + delay;
           display.display();
      }
    }

Server responds:
void loop() {
      server.handleClient();
}


user38447: My guess is, that you're wasting too much time within the drawing-part.
What is the value for delay? I guess you have a number too low chosen here. And you should really set this new time after you have updated the display by display.display();.
Your webserver doesn't respond because he's not called often enough inside this code.

42776: <p>I have simple example, where in loop is called webServer to handle clients and also text drawing on display.
The thing is that webServer is not responding, but when I remove second part of loop - drawing text to display then web server starts to work normally. </p>

<p>Server does not respond:
</p>

<pre class="lang-cpp prettyprint-override"><code> void loop() {
      server.handleClient();
      unsigned long timeNow = millis();
      if ((timeNow &gt; screenChangeTime))  {
          display.clear();
          display.setFont(ArialMT_Plain_16);
          display.setTextAlignment(TEXT_ALIGN_CENTER);
           display.drawString(12, 20,"Loaded: "+String(particles));
           screenChangeTime= timeNow + delay;
           display.display();
      }
    }
</code></pre>

<p>Server responds:</p>

<pre class="lang-cpp prettyprint-override"><code>void loop() {
      server.handleClient();
}
</code></pre>
 38447: <p>My guess is, that you're wasting too much time within the drawing-part.</p>

<p>What is the value for <code>delay</code>? I guess you have a number too low chosen here. And you should really set this new time <strong>after</strong> you have updated the display by <code>display.display();</code>.</p>

<p>Your webserver doesn't respond because he's not called often enough inside this code.</p>
