title: performance improvement: toString()
body: <p>We are developing quite big server app. Each action is tracked by log. There are many logs with calling of toString method. Unfortunatelly we need most of them on other hand we cannot track what happens on prod. 
  Is it make sense trying to improve toString method? Forexample put result of toString in memory and update if some field was updated.</p>
  
  <pre><code>example of my toString
  public classs InMessage{
  //declared 20+ fields
       @Override
        public String toString() {
         StringBuilder builder = new StringBuilder(this.getClass().getSimpleName());
         builder.append(": [");
         builder.append(super.toString());
         builder.append("; updateTime: ");
         builder.append(updateTime);
         //forexample 20 fields here
         builder.append(";]");
         return builder.toString();
       }}
  then we process InMessage in some way and log each action
       log.debug("We received inMessage: {}", inMessage);
  </code></pre>
  
  <p>after this discussion we decided to decrease number of logs where it's possible and nothing more. </p>