No, that is not for a specific case of high performance... It's for the non-specific case of keeping the code clear, understandable, and bug-free. The style was chosen for these reasons, not because it is more performant. It just happens to also be more performant than the layers of indirection that also harm understandability.

For a procedural code base, avoid subprocedures that are only called once.

For a pure functional codebase, e.g. Haskell, locally-scoped single-use functions can be beneficial.