CloneUtils' deepCloneObject method is performing a getAnnotation reflection call to acquire annotations of type: ReferenceCopy.
This call is being executed against every field in the process of deep cloning, and there are 3 fields in the application which actually have this annotation. With sufficient load, you'll hit another synchronize block in the nested declaredAnnotations() method in java.lang.reflect.Field. This will cause threads to be blocked and performance will degrade substantially. I hit this bottleneck around 45 to 60 concurrent threads doing lookups.
This also accounts for a good portion of cpu time which can be avoided by caching which fields have the annotation.