> every word you write in the source code will result in some predetermined machine instructions being executed Not strictly.. I wrote a partially optimizing

> every word you write in the source code will result in some predetermined machine instructions being executed Not strictly.. I wrote a partially optimizing Forth compiler that could combine compiled words when building new words that used them from the interpreter, analyze the generated assembly for unnecessary stack movement of arguments, and eliminate the stack movement and if necessary emit MOV instructions to fixup the output results into the correct input registers. This was not terribly difficult. The harder part was susequently decoding the concatenated x86 instruction streams to do this type of analysis, but once the PUSH and POP trains were spotted, they were super easy to just eliminate. With careful coding of the assembly words, you could guarantee that common expressions never needed any MOV fixups and could just pass results that were sitting directly in the registers.