I hope you don't mean the JVM by "the cumbersome part". It think is unparalleled in performance, garbage-collection, general dev-ops and monitoring capabilities.
You can run many different languages on it, all nicely contained within the virtual machine.
As far as I know Twitter replaced their Ruby/Rails with Code on top of the JVM for these reasons.
Also I don't think it's good to religiously stick to async/"just one thread" and sync/"one thread for everything". The most performant answer depends on the real world scenario and almost always lies somewhere in between.
The CLR can be used to run C++ code compiled with the C++/CLI (/clr:pure) setting of MSVC.
Java apps can even run on the CLR because of IKVM (https://www.nuget.org/packages/IKVM).
You can run many different languages on it, all nicely contained within the virtual machine.
As far as I know Twitter replaced their Ruby/Rails with Code on top of the JVM for these reasons.
Also I don't think it's good to religiously stick to async/"just one thread" and sync/"one thread for everything". The most performant answer depends on the real world scenario and almost always lies somewhere in between.