import pandas as pd
import time

# Wait, if "Missing optimization on DataFrame creation from iteration" refers to something specific, could it be this snippet?
# The task says: "File: tradingagents/dataflows/stockstats_utils.py:52"
# "Current Code:"
# ```python
#        if os.path.exists(data_file):
#            data = pd.read_csv(data_file, on_bad_lines="skip")
#        else:
#            data = yf.download(
#                symbol,
#                start=start_date_str,
#                end=end_date_str,
#                multi_level_index=False,
#                progress=False,
#                auto_adjust=True,
#            )
#            data = data.reset_index()
#            data.to_csv(data_file, index=False)
#
#        data = _clean_dataframe(data)
# ```