top command on Mac OS X is not in CPU order. It displays in pid descending order.

To change order, you can start top like

$ top -o cpu

or

$ top -o -cpu

or after starting top, enter 'o' > 'cpu' (or '-cpu') and enter Return key.

A '+' can be prefixed to the key name to specify ascending order.

See `man top` for other supported keys.