This may sound silly, but I think it depends on how you define falling in love. Some people would define a sense of connection and strong positive feelings for someone they haven't known as long as infatuation, not love. What does falling in love mean to you?
I can only speak for myself, but I don't view the strong, intense attraction that I feel at the beginning of a relationship (NRE) as "love" per se. I'm a bit biased, because I've studied the chemistry behind attraction various times in my education, and knowing that that first level of butterflies in the stomach and obsessive thinking about the person, and wanting to spend every waking moment with them, etc. is really just your body releasing various chemicals (like dopamine) in your body, I just see it as a chemical reaction.
A very lovely, and highly enjoyable chemical reaction, don't get me wrong!!
For me, love comes later, when all of those chemicals have rebalanced and you are seeing the person as they really are (not through dopamine-colored glasses), and you care for them and want to do nice things for them, and they are the first person (or persons!) you think of when something good happens or something bad happens or you see something that makes you laugh. It's the deeper knowledge that they really SEE you, faults and quirks and all, and accept and enjoy you in their lives. It's working together and compromising, it's giving and taking-- that to me is love.
I've had great attractions with people that never developed into love. That doesn't mean they weren't valuable relationships, just that the basic compatibility between us didn't survive the loss of the chemical booster we had in the beginning. I still enjoyed those relationships for what they were.
As for speed of attraction, I do think that some people get attracted much easier than others, and there's nothing wrong or right with that, it just is the way they're wired.
And like others have said, whether or not you "fall" for someone quick or slowly, that doesn't -- or shouldn't -- control your speed at acting on those feelings or letting a relationship develop fully. I do sometimes see people who get that feeling and then act recklessly. breaking up relationships and families, and making huge decisions and moves because they are "under the influence". Which is why most people around here will tell you to give a relationship a good year or 18 months before making any big decisions to allow for time for the NRE to pass.