MySQLdb is written in C. So you're comparing the speed of raw C code to pure Python (which runs on top of that C code). The vast difference in speed between pure C and Python has little to do with SQLAlchemy which I can assure you generates those objects as fast as possible while still maintaining proper behavior.
not really sure what you mean. MySQLdb, i.e. this project: http://mysql-python.sourceforge.net/FAQ.html ? When you ask this library to execute a query and return rows, the network communication with the MySQL server is done with C code, i.e. with _mysql . It doesn't make sense to say "_mysql is twice as fast as MySQLdb" - "_mysql" is an intrinsic component of it. The Python portion of MySQLdb does very little.
Here is from the FAQ included with the project:
"MySQLdb is a thin Python wrapper around ``_mysql`` which makes it
compatible with the Python DB API interface (version 2). In reality,
a fair amount of the code which implements the API is in ``_mysql``
for the sake of efficiency."
In fact, if you do want MySQLdb that's pure Python, there's an entirely separate project for that called pymsql: http://code.google.com/p/pymysql/. This library will be a lot slower than MySQLdb.
