read_excel: optimization

ixmap was being always converted into a list. Now if it is a range it
is left unchanged.

Author: salva

pandas/io/excel/_base.py

@@ -830,10 +830,11 @@ def _parse_sheet(
             # header indexes reference rows after removing skiprows, so we
             # create an index map from the without-skiprows to the
             # original indexes.
+            ixmap: Union(range, list[int])
             if skiprows is None:
-                ixmap = list(range(len(data)))
+                ixmap = range(len(data))
             elif is_integer(skiprows):
-                ixmap = list(range(skiprows, len(data)))
+                ixmap = range(skiprows, len(data))
             elif is_list_like(skiprows):
                 skiprows_set = set(cast(Sequence[int], skiprows))
                 ixmap = [ix for ix in range(len(data)) if ix not in skiprows_set]