You could take a look at GraalJS. It supports its own form of isolates and they can be created very fast, because an isolate setup is basically mmapping the pre

You could take a look at GraalJS. It supports its own form of isolates and they can be created very fast, because an isolate setup is basically mmapping the pre-calculated heap into another area of memory and starting up another thread. I never measured it but it shouldn't be particularly slow. It also means you can mix languages.