How can I speed up my boot time?

The best way would be to install an SSD HD in your Mac Pro and put the OS and apps on it - leave your data on the spinning one.

You can also check for login items. Go to the Accounts system preference and click the login items tab. Do you have a lot of free HD space - a full/nearly full HD can slow you down as well.

Is it slower than it used to be?

In Lion, it's called Users & Groups. Open that and check the login items.