title: JVM option XX:UseFastEmptyMethods/XX:UseFastAccessorMethods
body: <p>While looking at <a href="https://stackoverflow.com/questions/142357/what-are-the-best-jvm-settings-for-eclipse">possible JVM flags for optimizing launching startup time</a> of my RCP product, I found these attractively-named <code>-XX:UseFastEmptyMethods</code> and <code>-XX:UseFastAccessorMethods</code>.</p>
  
  <p>It seems that those flags were available on JDK-6 (and on by default), while they were defaulted to off on JDK-7. Also, I read that the trade-off for this optimization is that they do not increase method invocation counters. </p>
  
  <p>What is the impact of not using invocation counters? Does that affect garbage collection?</p>