[faq] fast_executemany does not work - gordthompson/sqlalchemy-access GitHub Wiki

That's right. It doesn't.

pyodbc's fast_executemany feature depends on an internal ODBC mechanism named "parameter arrays" and the Microsoft Access ODBC driver does not support them, so fast_executemany simply cannot work with this dialect.

Related:

[pandas] faster alternative to .to_sql() for large uploads