Anno 1404 can't do much with more than two CPU cores. As the frame rates show, an older single-core CPU would be overwhelmed.
Up to 680 MB of graphics memory is used with AA activated. The game reacts to CPU overclocking by dropping utilization a bit when we shift from 3 GHz to 4 GHz. This doesn't yield more frames per second, though.
If you want better performance in this title, you'll want at least a dual-core CPU and a graphics card upgrade.