Why OptaPlanner example runs very slow on WildFly

Question

I modify the OptaPlanner 6.5 course timetabling example to a REST service using the vehiclerouting web example as a template. We found that the web version of course timetabling run very slow as compared to pure Java version of course timetabling.

For example, the pure Java edition timetabling system can get a 0Hard/-352Soft score. But the web edition can only get -7Hard/-1108Soft. No matter how long we run the example.

The web edition is hosted in a WildFly 9. The JVM versions we use are both Oracle JVM 1.8; Further, we tried using WildFly 10. And the result is the same.

Can anyone shed some light on it? I want get the same performance in web edition as Java edition.