A compiled functional language doesn't (have to) have much overhead compared to a dynamic language with a fancy runtime.
The same could be said of a compiled OO language though couldn't it?
Yes, of course! I may have misunderstand the thread, I just meant to address the smalltalk vs functional comparison.
Although I guess smalltalk has had a (JIT) compiler for a long time, so it's more about runtime/bytecode efficiency (with dynamic types) vs native compilation.