It greatly depends on your forth compiler. Most hobby forth compilers are simple, and just lay down addresses to words or native call instructions, sometimes w

It greatly depends on your forth compiler. Most hobby forth compilers are simple, and just lay down addresses to words or native call instructions, sometimes with inlining. These aren't slow, but they won't get close to C optimized by modern compilers. Production Forths like SwiftForth apparently have optimizing compilers, but I've never used them.