Very much the contrary! In C all the syntax and control structures have to be built into the language; this makes C a much more complex language than Forth, because in Forth the language and interpreter don't even have to support things like comments, string literals, variables, and control flow. Because of immediate words, all of that can be built on top of the base language in high-level Forth, and almost always is. This allows the language itself to be enormously simpler.

It's also generally the case that in a native-code-compiling Forth the mapping from the Forth source to the machine code emitted is very much simpler and more direct than in C; as Virgil implicitly pointed out, the machine code is generally more or less in the same order as the source code, which in C it is not, and you don't have a bunch of implicit type conversions, ad-hoc polymorphic arithmetic operators, and so on. (It doesn't have to be more direct, since you can do arbitrary computation at compile time, but it usually is.)