Using activerecord-import

This is an example showing usage of Zach Dennis' activerecord-import gem. Instead of playing with tutorial databases, I decided to create a somewhat real database that can be of use to all. I came across public zip-code database for US cities.
So, this is a simple Rails application (nothing there yet) with three models: City, Code and State. And here are the straightforward migrations. Some may argue if we need the models this way, but that's a separate thing.
What I wanted to do was use Zach Dennis' excellent activerecord-import gem to see if I can seed the database with the zips.csv I have created (modified from original at sf.net).
Of course, the seeding should be fast. But more importantly, it should be correct.
So, I am going to ask Zach if he can take a look here.

After you clone this repository, just do the following:

Modify database.yml to your environment. (For MySQL, just move database.yml.mysql to database.yml)
See db/seeds.rb. It has two methods: seed_from and import_from which I think seed the database correctly.
See how import_from loses the API goodies of Rails AR to use models to modify database.
But import_from is still way faster for such a trivial database of 33100 records.
My question to Zach is whether this is the right way to use activerecord-import gem. Of course, when I do this, I get WARNING: Can't mass-assign protected attributes: id all over, but I see no way around it.

Some observations

The time command shows some result for this import is:

MySQL (server on nearest machine on the network): rake db:setup 549.83s user 0.96s system 99% cpu 9:12.39 total. The server is a Quad-core Ubuntu, sitting next to my desktop.
SQLite (Local): rake db:setup 562.80s user 24.32s system 85% cpu 11:27.61 total. This is on a Quad-core Ubuntu.
My understanding is that this (~9 minutes' wall-clock time for MySQL and that of ~12 minutes for local SQLite) is slow. What am I doing wrong?
I understand that lot of time is spent in logging the generated SQL. But is that a factor?
I see "SHOW VARIABLES like 'max_allowed_packet';" in case of MySQL. I believe that setting on my server is all right (its value in my.cnf is default = 16M). If not, what should that be?
The generated database itself is correct, as far as I can tell, from my testing with rails console (e.g. using stuff like City.all, City.all.where("name=?", "Phoenix").