ODBC Connection being extremely slow

If possible, you may want to use the SQLSRV driver instead. http://php.net/manual/en/intro.sqlsrv.php

However, when you say you used the same connection settings outside of CodeIgniter, does that mean you've setup a simple PHP script to run

Code:

$connection = odbc_connect('Driver={SQL Server};Server=MATTHEW;Database=db1;', 'root', 'root');

and check the result?

Bonfire

Practical CodeIgniter 3
CodeIgniter Testing Guide