Okay, let me try to explain the scenario via a famous concept in Solid State Electronics.

The Energy Gap between Valence Band and Conduction Band.
So, there is an energy gap existing between the valence and conduction band of an element. Somewhat like this.

Let us symbolize the Valence Band as "No feelings" and the Conduction Band as "Love". When an electron crossed the energy gap between the two, in other words, when an relationship passes through certain stages, we call them to be in Love. This takes time and energy.
For some of us this gap isn't that large, it's pretty easy to get to their hearts (Conductors). Some are a little bit more protective and require some effort (Semiconductors). While some are just plain impossible to fall in love with (Insulators).

While for elements, it may seem quite simple, the human energy gap often has layers to penetrate.

Love at first sight, explained according to this concept would be something like,

Since, Love at first sight doesn't provide the time or energy, to accommodate this transition, one can only speculate that, the phenomena is more like,

So, ask yourself, when your electron is making this transition, are you actually experiencing all these stages in a smaller time frame or are you skipping some vital ones?
Most of the time it's seen that the Infatuation and Lust energies are strong enough to make this happen. Although a transition which occurred in such a small time and with such futile parameters, is highly likely to crash and burn as soon as a small amount of heat is applied to it. The bond will break at the slightest flame of a bunsen burner or a simple mishap of life.
Not only are you missing out on all the subtle emotions at the various stages, but you are depriving your conducting electron (the guy/girl) of them.

Bottom line, No, I do not believe in Love at first sight, and I apologize for the long and highly symbolic answer.