diff --git a/src/input/return_enums.rs b/src/input/return_enums.rs
index e46b8ffe3..b63c12aa0 100644
--- a/src/input/return_enums.rs
+++ b/src/input/return_enums.rs
@@ -64,9 +64,16 @@ fn validate_iter_to_vec<'a, 's>(
         match validator.validate(py, item, extra, slots, recursion_guard) {
             Ok(item) => output.push(item),
             Err(ValError::LineErrors(line_errors)) => {
+                if !extra.exhaustive {
+                    return Err(ValError::Omit);
+                }
                 errors.extend(line_errors.into_iter().map(|err| err.with_outer_location(index.into())));
             }
-            Err(ValError::Omit) => (),
+            Err(ValError::Omit) => {
+                if !extra.exhaustive {
+                    return Err(ValError::Omit);
+                }
+            }
             Err(err) => return Err(err),
         }
     }
diff --git a/src/validators/generator.rs b/src/validators/generator.rs
index f79ac1703..b7df4ba1f 100644
--- a/src/validators/generator.rs
+++ b/src/validators/generator.rs
@@ -239,6 +239,7 @@ impl InternalValidator {
             field: self.field.as_deref(),
             strict: self.strict,
             context: self.context.as_ref().map(|data| data.as_ref(py)),
+            exhaustive: true,
         };
         self.validator
             .validate(py, input, &extra, &self.slots, &mut self.recursion_guard)
diff --git a/src/validators/mod.rs b/src/validators/mod.rs
index 40c45afc1..40dc72c8c 100644
--- a/src/validators/mod.rs
+++ b/src/validators/mod.rs
@@ -196,6 +196,7 @@ impl SchemaValidator {
             field: Some(field.as_str()),
             strict,
             context,
+            exhaustive: true,
         };
         let r = self
             .validator
@@ -450,6 +451,8 @@ pub struct Extra<'a> {
     pub strict: Option<bool>,
     /// context used in validator functions
     pub context: Option<&'a PyAny>,
+    // if we should do exhaustive validation
+    pub exhaustive: bool,
 }
 
 impl<'a> Extra<'a> {
@@ -457,6 +460,7 @@ impl<'a> Extra<'a> {
         Extra {
             strict,
             context,
+            exhaustive: true,
             ..Default::default()
         }
     }
@@ -469,6 +473,16 @@ impl<'a> Extra<'a> {
             field: self.field,
             strict: Some(true),
             context: self.context,
+            exhaustive: self.exhaustive,
+        }
+    }
+    pub fn with_exhaustiveness(&self, exhaustive: bool) -> Self {
+        Self {
+            data: self.data,
+            field: self.field,
+            strict: Some(true),
+            context: self.context,
+            exhaustive,
         }
     }
 }
diff --git a/src/validators/typed_dict.rs b/src/validators/typed_dict.rs
index 189e1ff98..d239fb571 100644
--- a/src/validators/typed_dict.rs
+++ b/src/validators/typed_dict.rs
@@ -188,6 +188,7 @@ impl Validator for TypedDictValidator {
             field: None,
             strict: extra.strict,
             context: extra.context,
+            exhaustive: true,
         };
 
         macro_rules! process {
diff --git a/src/validators/union.rs b/src/validators/union.rs
index 324b7e3d8..c6a4cee40 100644
--- a/src/validators/union.rs
+++ b/src/validators/union.rs
@@ -85,6 +85,17 @@ impl Validator for UnionValidator {
         recursion_guard: &'s mut RecursionGuard,
     ) -> ValResult<'data, PyObject> {
         if extra.strict.unwrap_or(self.strict) {
+            // 1st pass: non exhaustive
+            let non_exhaustive_extra = extra.with_exhaustiveness(false);
+            if let Some(res) = self
+                .choices
+                .iter()
+                .map(|validator| validator.validate(py, input, &non_exhaustive_extra, slots, recursion_guard))
+                .find(ValResult::is_ok)
+            {
+                return res;
+            }
+
             let mut errors: Option<Vec<ValLineError>> = match self.custom_error {
                 None => Some(Vec::with_capacity(self.choices.len())),
                 _ => None,
@@ -110,7 +121,7 @@ impl Validator for UnionValidator {
         } else {
             // 1st pass: check if the value is an exact instance of one of the Union types,
             // e.g. use validate in strict mode
-            let strict_extra = extra.as_strict();
+            let strict_extra = extra.as_strict().with_exhaustiveness(false);
             if let Some(res) = self
                 .choices
                 .iter()
diff --git a/tests/benchmarks/test_micro_benchmarks.py b/tests/benchmarks/test_micro_benchmarks.py
index 815a3498e..a2afcdb6f 100644
--- a/tests/benchmarks/test_micro_benchmarks.py
+++ b/tests/benchmarks/test_micro_benchmarks.py
@@ -837,6 +837,20 @@ def test_smart_union_core(self, benchmark):
 
         benchmark(v.validate_python, 1)
 
+    @pytest.mark.benchmark(group='smart-union')
+    def test_smart_union_deep(self, benchmark):
+        v = SchemaValidator(
+            {
+                'type': 'union',
+                'choices': [
+                    {'type': 'list', 'items_schema': {'type': 'str'}},
+                    {'type': 'list', 'items_schema': {'type': 'int'}},
+                ],
+            }
+        )
+        data = [1] * 1_000
+        benchmark(v.validate_python, data)
+
     @skip_pydantic
     @pytest.mark.benchmark(group='smart-union')
     def test_smart_union_pyd(self, benchmark):