I’m sympathetic to the argument that C isn’t realistically a “high-level assembler” any more, but if there is low-hanging performance fruit available for a language free to dispense with C’s PDP-11-flavored abstractions, I haven’t seen practical examples of it.

If anything, more modern languages (eg Java) have to contort their data representations to build, say, “structs of arrays” that are highly efficient on modern CPUs (and trivial to express in C!)

I’m very curious to hear of any recent languages that are designed expressly with “mechanical sympathy” in mind.