How is that instance pooling with EJBs can improve performance? Wouldn't you be able to accomplish the same performance just with threads like a java servlet?
Or perhaps instance pooling with EJBs happens for another reason?
I think instance pooling is used when the beans are expensive to construct. By letting the next request reuse the same bean you don't have to construct another instance.
If the bean itself is cheap to construct and the cost is in the work that it's doing, then instance pooling isn't worth the hassle.