diff --git a/homeassistant/core.py b/homeassistant/core.py
index a30aed22322..f01f8188bc0 100644
--- a/homeassistant/core.py
+++ b/homeassistant/core.py
@@ -1693,7 +1693,7 @@ class Service:
 class ServiceCall:
     """Representation of a call to a service."""
 
-    __slots__ = ["domain", "service", "data", "context", "return_response"]
+    __slots__ = ("domain", "service", "data", "context", "return_response")
 
     def __init__(
         self,
@@ -1704,8 +1704,8 @@ class ServiceCall:
         return_response: bool = False,
     ) -> None:
         """Initialize a service call."""
-        self.domain = domain.lower()
-        self.service = service.lower()
+        self.domain = domain
+        self.service = service
         self.data = ReadOnlyDict(data or {})
         self.context = context or Context()
         self.return_response = return_response
@@ -1890,15 +1890,20 @@ class ServiceRegistry:
 
         This method is a coroutine.
         """
-        domain = domain.lower()
-        service = service.lower()
         context = context or Context()
         service_data = service_data or {}
 
         try:
             handler = self._services[domain][service]
         except KeyError:
-            raise ServiceNotFound(domain, service) from None
+            # Almost all calls are already lower case, so we avoid
+            # calling lower() on the arguments in the common case.
+            domain = domain.lower()
+            service = service.lower()
+            try:
+                handler = self._services[domain][service]
+            except KeyError:
+                raise ServiceNotFound(domain, service) from None
 
         if return_response:
             if not blocking:
@@ -1938,8 +1943,8 @@ class ServiceRegistry:
         self._hass.bus.async_fire(
             EVENT_CALL_SERVICE,
             {
-                ATTR_DOMAIN: domain.lower(),
-                ATTR_SERVICE: service.lower(),
+                ATTR_DOMAIN: domain,
+                ATTR_SERVICE: service,
                 ATTR_SERVICE_DATA: service_data,
             },
             context=context,
@@ -1947,7 +1952,10 @@ class ServiceRegistry:
 
         coro = self._execute_service(handler, service_call)
         if not blocking:
-            self._run_service_in_background(coro, service_call)
+            self._hass.async_create_task(
+                self._run_service_call_catch_exceptions(coro, service_call),
+                f"service call background {service_call.domain}.{service_call.service}",
+            )
             return None
 
         response_data = await coro
@@ -1959,49 +1967,42 @@ class ServiceRegistry:
             )
         return response_data
 
-    def _run_service_in_background(
+    async def _run_service_call_catch_exceptions(
         self,
         coro_or_task: Coroutine[Any, Any, Any] | asyncio.Task[Any],
         service_call: ServiceCall,
     ) -> None:
         """Run service call in background, catching and logging any exceptions."""
-
-        async def catch_exceptions() -> None:
-            try:
-                await coro_or_task
-            except Unauthorized:
-                _LOGGER.warning(
-                    "Unauthorized service called %s/%s",
-                    service_call.domain,
-                    service_call.service,
-                )
-            except asyncio.CancelledError:
-                _LOGGER.debug("Service was cancelled: %s", service_call)
-            except Exception:  # pylint: disable=broad-except
-                _LOGGER.exception("Error executing service: %s", service_call)
-
-        self._hass.async_create_task(
-            catch_exceptions(),
-            f"service call background {service_call.domain}.{service_call.service}",
-        )
+        try:
+            await coro_or_task
+        except Unauthorized:
+            _LOGGER.warning(
+                "Unauthorized service called %s/%s",
+                service_call.domain,
+                service_call.service,
+            )
+        except asyncio.CancelledError:
+            _LOGGER.debug("Service was cancelled: %s", service_call)
+        except Exception:  # pylint: disable=broad-except
+            _LOGGER.exception("Error executing service: %s", service_call)
 
     async def _execute_service(
         self, handler: Service, service_call: ServiceCall
     ) -> ServiceResponse:
         """Execute a service."""
-        if handler.job.job_type == HassJobType.Coroutinefunction:
-            return await cast(
-                Callable[[ServiceCall], Awaitable[ServiceResponse]],
-                handler.job.target,
-            )(service_call)
-        if handler.job.job_type == HassJobType.Callback:
-            return cast(Callable[[ServiceCall], ServiceResponse], handler.job.target)(
-                service_call
-            )
-        return await self._hass.async_add_executor_job(
-            cast(Callable[[ServiceCall], ServiceResponse], handler.job.target),
-            service_call,
-        )
+        job = handler.job
+        target = job.target
+        if job.job_type == HassJobType.Coroutinefunction:
+            if TYPE_CHECKING:
+                target = cast(Callable[..., Coroutine[Any, Any, _R]], target)
+            return await target(service_call)
+        if job.job_type == HassJobType.Callback:
+            if TYPE_CHECKING:
+                target = cast(Callable[..., _R], target)
+            return target(service_call)
+        if TYPE_CHECKING:
+            target = cast(Callable[..., _R], target)
+        return await self._hass.async_add_executor_job(target, service_call)
 
 
 class Config: