Do not always check if __main__ in result when pickling (dask#8443)

distributed/protocol/pickle.py

@@ -67,14 +67,19 @@ def dumps(x, *, buffer_callback=None, protocol=HIGHEST_PROTOCOL):
             buffers.clear()
             pickler.dump(x)
             result = f.getvalue()
-        if b"__main__" in result or (
+
+        if not _always_use_pickle_for(x) and (
             CLOUDPICKLE_GE_20
             and getattr(inspect.getmodule(x), "__name__", None)
             in cloudpickle.list_registry_pickle_by_value()
+            or (
+                len(result) < 1000
+                # Do this very last since it's expensive
+                and b"__main__" in result
+            )
         ):
-            if len(result) < 1000 or not _always_use_pickle_for(x):
-                buffers.clear()
-                result = cloudpickle.dumps(x, **dump_kwargs)
+            buffers.clear()
+            result = cloudpickle.dumps(x, **dump_kwargs)
     except Exception:
         try:
             buffers.clear()