For Gmail to reach full interactivity it takes at least 6 seconds for me quite often. Keep in mind that after the interface initially shows up, it's still very sluggish for a few seconds as it loads in Google+, the chat section, etc.
That said, I recently found out about the /h/ option in this thread and it loads instantaneously--faster than FastMail.
That said, I recently found out about the /h/ option in this thread and it loads instantaneously--faster than FastMail.