As documented in https://wiki.php.net/rfc/use_global_elements, the engine (by default) does a local namespace
lookup, then falls back to global namespace when first calling a global function referenced in namespaced code,
unless that function is referenced via fully qualified name (FQN).
By using the FQN, the actual symbol can be looked up at compile-time, both by the PHP engine and by static analysis
tooling, allowing for compiler (in particular) optimizations to replace known hot-path functions with specialized opcodes.
Sadly, no actual benchmark at hand: the improvements can be minimal or massive, depending on where this library is
used (tight loops being most relevant).
Marco Pivetta
Ben Ramsey
Martin Hujer
Jildert Miedema
Ben Peachey
Andreas Möller