Online, definitely online. A friend of mine and myself were curious about this when we first began school, so we did an experiment. Besides us two, we enlisted two others to try this with us. Two of us did it online, and the other two mailed it in. We did this our freshman year and our sophomore year. The first year, the online app got it done in 4 days (this does not count the four days it took to apply for a pin number online and get it in the mail before we could complete the online application.) Once you have your pin number, it's quicker. The mailed apps got their results in barely over three weeks. It should be noted, however, that it is faster the next year when you mail it because your basic info will already be in the system for the financial aid people to pull up.
The second year, online apps got results in three days (with no down time to get the pin number because it stays the same unless you change it.) The mailed apps got results in just shy of two weeks. I think it was 12 days (not just business days.) We've since not been going to the same college and lost touch, but I still do mine online with my pin number, and I always get results within three to four days. Your designated school is automatically sent the results, so you don't have to worry about that. But, the school is the one that reads/interprets the results to determine whether or not you get anything. What I mean is, the web results you see are not going to say, "You get the Pell Grant." It may say you're eligible, but your school has the final decision on that.
Hope this helped some.