Everything has a cost though. The one thing we lose is the ability for hotspot to change its mind and recompile code based on usage patterns I've toyed with graalvm for some uses and ended up with lost performance. Also a key note is that it only supports a pretty naive serialgc right now which is a big limitation. Bellsoft has a parallelgc which probably plays a little better, but we're always going to need to play trade-offs until they can support the more robust GC impls
You can try to use Graal as a JIT compiler as well, in case of Scala for example that has a bit more indirection on average it can cause some speedups.