diff --git a/ports/zephyr-cp/cptools/build_circuitpython.py b/ports/zephyr-cp/cptools/build_circuitpython.py
index 55c069a1ddc..edc9422377b 100644
--- a/ports/zephyr-cp/cptools/build_circuitpython.py
+++ b/ports/zephyr-cp/cptools/build_circuitpython.py
@@ -369,6 +369,8 @@ async def build_circuitpython():  # noqa: C901
     lto = cmake_args.get("LTO", "n") == "y"
     circuitpython_flags.append(f"-DCIRCUITPY_ENABLE_MPY_NATIVE={1 if enable_mpy_native else 0}")
     circuitpython_flags.append(f"-DCIRCUITPY_FULL_BUILD={1 if full_build else 0}")
+    circuitpython_flags.append("-DCIRCUITPY_OPT_LOAD_ATTR_FAST_PATH=1")
+    circuitpython_flags.append(f"-DCIRCUITPY_OPT_MAP_LOOKUP_CACHE={1 if full_build else 0}")
     circuitpython_flags.append(f"-DCIRCUITPY_SETTINGS_TOML={1 if full_build else 0}")
     circuitpython_flags.append(f"-DMICROPY_PY_ASYNC_AWAIT={1 if full_build else 0}")
     circuitpython_flags.append(f"-DMICROPY_PY_ASYNCIO={1 if full_build else 0}")