diff --git a/.github/workflows/perf.yml b/.github/workflows/perf.yml
new file mode 100644
index 000000000..30ac5570c
--- /dev/null
+++ b/.github/workflows/perf.yml
@@ -0,0 +1,50 @@
+name: Run Performance tests
+
+on: [pull_request]
+
+jobs:
+  bench:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+
+      - name: Get full Python version
+        id: full-python-version
+        shell: bash
+        run: echo ::set-output name=version::$(python -c "import sys; print('-'.join(str(v) for v in sys.version_info))")
+
+      - name: Install poetry
+        shell: bash
+        run: |
+          python -m pip install poetry
+          echo "$HOME/.poetry/bin" >> $GITHUB_PATH
+
+      - name: Configure poetry
+        shell: bash
+        run: poetry config virtualenvs.in-project true
+
+      - name: Set up cache
+        uses: actions/cache@v2
+        id: cache
+        with:
+          path: .venv
+          key: venv-${{ runner.os }}-${{ steps.full-python-version.outputs.version }}-${{ hashFiles('**/poetry.lock') }}
+
+      - name: Ensure cache is healthy
+        if: steps.cache.outputs.cache-hit == 'true'
+        shell: bash
+        run: poetry run pip --version >/dev/null 2>&1 || rm -rf .venv
+
+      - name: Install dependencies
+        shell: bash
+        run: |
+          poetry run python -m pip install pip -U
+          poetry install
+
+      - name: Run benchmarks
+        run:
+          poetry run python -m asv continuous master ${{ github.ref }}
diff --git a/src/betterproto/__init__.py b/src/betterproto/__init__.py
index 3cee8887e..f562b664c 100644
--- a/src/betterproto/__init__.py
+++ b/src/betterproto/__init__.py
@@ -724,11 +724,13 @@ def _betterproto(self) -> ProtoClassMetadata:
         It may be initialized multiple times in a multi-threaded environment,
         but that won't affect the correctness.
         """
-        meta = getattr(self.__class__, "_betterproto_meta", None)
-        if not meta:
+        cls = self.__class__
+        try:
+            return cls._betterproto_meta
+        except AttributeError:
             meta = ProtoClassMetadata(self.__class__)
-            self.__class__._betterproto_meta = meta  # type: ignore
-        return meta
+            cls._betterproto_meta = meta  # type: ignore
+            return meta
 
     def __bytes__(self) -> bytes:
         """
@@ -846,7 +848,7 @@ def _type_hint(cls, field_name: str) -> Type:
     @classmethod
     def _type_hints(cls) -> Dict[str, Type]:
         module = sys.modules[cls.__module__]
-        return get_type_hints(cls, vars(module))
+        return get_type_hints(cls, module.__dict__, {})
 
     @classmethod
     def _cls_for(cls, field: dataclasses.Field, index: int = 0) -> Type: