diff --git a/benches/eval_module.rs b/benches/eval_module.rs
new file mode 100644
index 00000000..98843eeb
--- /dev/null
+++ b/benches/eval_module.rs
@@ -0,0 +1,87 @@
+#![feature(test)]
+
+///! Test evaluating with scope
+extern crate test;
+
+use rhai::{module_resolvers::StaticModuleResolver, Engine, Module, OptimizationLevel};
+use test::Bencher;
+
+#[bench]
+fn bench_eval_module_merged(bench: &mut Bencher) {
+    let script = r#"
+        fn foo(x) { x + 1 }
+        fn bar(x) { foo(x) }
+    "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile(script).unwrap();
+
+    let module = Module::eval_ast_as_new(Default::default(), &ast, true, &engine).unwrap();
+
+    let mut resolver = StaticModuleResolver::new();
+    resolver.insert("testing", module);
+    engine.set_module_resolver(Some(resolver));
+
+    let ast = engine
+        .compile(
+            r#"
+                fn foo(x) { x - 1 }
+                import "testing" as t;
+                t::bar(41)
+    "#,
+        )
+        .unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
+
+#[bench]
+fn bench_eval_module_unmerged(bench: &mut Bencher) {
+    let script = r#"
+        fn foo(x) { x + 1 }
+        fn bar(x) { foo(x) }
+    "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile(script).unwrap();
+
+    let module = Module::eval_ast_as_new(Default::default(), &ast, false, &engine).unwrap();
+
+    let mut resolver = StaticModuleResolver::new();
+    resolver.insert("testing", module);
+    engine.set_module_resolver(Some(resolver));
+
+    let ast = engine
+        .compile(
+            r#"
+                fn foo(x) { x - 1 }
+                import "testing" as t;
+                t::bar(41)
+    "#,
+        )
+        .unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
+
+#[bench]
+fn bench_eval_function_call(bench: &mut Bencher) {
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine
+        .compile(
+            r#"
+                fn foo(x) { x - 1 }
+                fn bar(x) { foo(x) }
+                bar(41)
+    "#,
+        )
+        .unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
diff --git a/doc/src/rust/modules/ast.md b/doc/src/rust/modules/ast.md
index 0348579a..fed0cb09 100644
--- a/doc/src/rust/modules/ast.md
+++ b/doc/src/rust/modules/ast.md
@@ -27,9 +27,13 @@ functions exposed by the module and the namespace that they can access:
 
 | `merge_namespaces` value | Description                                      |      Namespace      | Performance | Call global functions | Call functions in same module |
 | :----------------------: | ------------------------------------------------ | :-----------------: | :---------: | :-------------------: | :---------------------------: |
-|          `true`          | encapsulate entire `AST` into each function call | module, then global |   slower    |          yes          |              yes              |
+|          `true`          | encapsulate entire `AST` into each function call | module, then global |  2x slower  |          yes          |              yes              |
 |         `false`          | register each function independently             |     global only     |    fast     |          yes          |              no               |
 
+If the ultimate intention is to load the [module] directly into an [`Engine`] via `Engine::load_package`,
+set `merge_namespaces` to `false` because there will not be any _module_ namespace as `Engine::load_package`
+flattens everything into the _global_ namespace anyway.
+
 
 Examples
 --------
@@ -78,7 +82,9 @@ let ast = engine.compile(r#"
 // a copy of the entire 'AST' into each function, allowing functions in the module script
 // to cross-call each other.
 //
-// This incurs additional overhead, avoidable by setting 'merge_namespaces' to false.
+// This incurs additional overhead, avoidable by setting 'merge_namespaces' to false
+// which makes function calls 2x faster but at the expense of not being able to cross-call
+// functions in the same module script.
 let module = Module::eval_ast_as_new(Scope::new(), &ast, true, &engine)?;
 
 // 'module' now contains:
diff --git a/src/fn_register.rs b/src/fn_register.rs
index 5c519d4c..3df06d5e 100644
--- a/src/fn_register.rs
+++ b/src/fn_register.rs
@@ -178,7 +178,7 @@ macro_rules! def_register {
     (imp $abi:ident : $($par:ident => $arg:expr => $mark:ty => $param:ty => $let:stmt => $clone:expr),*) => {
     //   ^ function ABI type
     //                  ^ function parameter generic type name (A, B, C etc.)
-//                                    ^ call argument(like A, *B, &mut C etc)
+    //                                ^ call argument(like A, *B, &mut C etc)
     //                                            ^ function parameter marker type (T, Ref<T> or Mut<T>)
     //                                                         ^ function parameter actual type (T, &T or &mut T)
     //                                                                      ^ argument let statement
diff --git a/src/module/mod.rs b/src/module/mod.rs
index 83a5ca24..3981ead4 100644
--- a/src/module/mod.rs
+++ b/src/module/mod.rs
@@ -1260,8 +1260,12 @@ impl Module {
     ///   defined in the module, are _merged_ into a _unified_ namespace before each call.
     ///   Therefore, all functions will be found, at the expense of some performance.
     ///
-    /// * If `false`, each function is registered independently and cannot cross-call
-    ///   each other. Functions are searched in the global namespace.
+    /// * If `false`, each function is registered independently and cannot cross-call each other.
+    ///   Functions are searched in the global namespace.
+    ///   This is roughly 2x faster than the `true` case.
+    ///
+    /// Set `merge_namespaces` to `false` if the ultimate intention is to load the module
+    /// via `Engine::load_package` because it does not create any module namespace.
     ///
     /// # Examples
     ///
diff --git a/tests/modules.rs b/tests/modules.rs
index e1a8bae6..f14a8276 100644
--- a/tests/modules.rs
+++ b/tests/modules.rs
@@ -361,3 +361,40 @@ fn test_module_str() -> Result<(), Box<EvalAltResult>> {
 
     Ok(())
 }
+
+#[test]
+fn test_module_ast_namespace() -> Result<(), Box<EvalAltResult>> {
+    let script = r#"
+        fn foo(x) { x + 1 }
+        fn bar(x) { foo(x) }
+    "#;
+
+    let mut engine = Engine::new();
+
+    let ast = engine.compile(script)?;
+
+    let module = Module::eval_ast_as_new(Default::default(), &ast, true, &engine)?;
+
+    let mut resolver = StaticModuleResolver::new();
+    resolver.insert("testing", module);
+    engine.set_module_resolver(Some(resolver));
+
+    assert_eq!(
+        engine.eval::<INT>(r#"import "testing" as t; t::foo(41)"#)?,
+        42
+    );
+    assert_eq!(
+        engine.eval::<INT>(r#"import "testing" as t; t::bar(41)"#)?,
+        42
+    );
+    assert_eq!(
+        engine.eval::<INT>(r#"fn foo(x) { x - 1 } import "testing" as t; t::foo(41)"#)?,
+        42
+    );
+    assert_eq!(
+        engine.eval::<INT>(r#"fn foo(x) { x - 1 } import "testing" as t; t::bar(41)"#)?,
+        42
+    );
+
+    Ok(())
+}