> Most of the slowness I encounter though is with specific frameworks, not the language/jvm
Part of the problem is that those also happen to be the frameworks that the vast majority of the community uses.
The Java zealots also tend to ignore all of the problems associated with AOT Java compilers and the fact that it will most likely be a few years before value objects are finalized and in a released version of Java. Even then, a ton of Java developers won't be able to use any features beyond Java 8 or 11 since a lot of companies don't want to give up the ability to easily use their libraries on Android.
I do sometimes use Go for its contiguous memory layout and await JEP 169: Value Objects from Project Valhalla.