As T91855 is resolved we now have iojs available on Jessie. This means that we can start switching RESTBase hosts to a modern version of v8. Apart from heapdump (only used for debugging) RESTBase has no binary dependencies, so we can simply switch one node at a time.
The expected performance benefit is significant. In local testing with ab -n 10000 -c 20 http://localhost:7231/en.wikipedia.org/v1/page/html/Foobar, iojs improves throughput from about 840 req/s to 940 req/s.