PERF: DataFrame(ndarray)

pandas/core/internals/construction.py

@@ -386,7 +386,9 @@ def ndarray_to_mgr(
     if len(columns) == 0:
         block_values = []
 
-    return create_block_manager_from_blocks(block_values, [columns, index])
+    return create_block_manager_from_blocks(
+        block_values, [columns, index], verify_integrity=False
+    )
 
 
 def _check_values_indices_shape_match(

pandas/core/internals/managers.py

@@ -1553,6 +1553,11 @@ def is_consolidated(self) -> bool:
         return self._is_consolidated
 
     def _consolidate_check(self) -> None:
+        if len(self.blocks) == 1:
+            # fastpath
+            self._is_consolidated = True
+            self._known_consolidated = True
+            return
         dtypes = [blk.dtype for blk in self.blocks if blk._can_consolidate]
         self._is_consolidated = len(dtypes) == len(set(dtypes))
         self._known_consolidated = True
@@ -1775,10 +1780,20 @@ def _equal_values(self: T, other: T) -> bool:
 
 
 def create_block_manager_from_blocks(
-    blocks: list[Block], axes: list[Index], consolidate: bool = True
+    blocks: list[Block],
+    axes: list[Index],
+    consolidate: bool = True,
+    verify_integrity: bool = True,
 ) -> BlockManager:
+    # If verify_integrity=False, then caller is responsible for checking
+    #  all(x.shape[-1] == len(axes[1]) for x in blocks)
+    #  sum(x.shape[0] for x in blocks) == len(axes[0])
+    #  set(x for for blk in blocks for x in blk.mgr_locs) == set(range(len(axes[0])))
+    #  all(blk.ndim == 2 for blk in blocks)
+    # This allows us to safely pass verify_integrity=False
+
     try:
-        mgr = BlockManager(blocks, axes)
+        mgr = BlockManager(blocks, axes, verify_integrity=verify_integrity)
 
     except ValueError as err:
         arrays = [blk.values for blk in blocks]