I’m afraid it’s basically out of the question. We can’t even use stable features of recent JDKs, as we have to support older JDKs.
It may be interesting to evaluate what performance we could, theoretically, gain. It’s possible for someone to alter the codegen in a branch, and do some measurements with that. However, it is very unlikely that we will merge such a branch, because it will be effectively dead code for the next 5 to 10 years.