Does NEX 7 auto focus as fast as a DSLR

It's astoundingly slower than a Nikon D800, as mentioned, but the D800 is one of the quickest focusing bodies on the market.

Having said that, the NEX-7's focus speed depends largely on the focus setting used and is nothing to sneeze at. If you use selectable focus and pick the center focus point, for example, it will focus almost instantaneously. If you activate all the focal points, it will focus almost as quickly, but it may not focus on the area you wish to converge upon.

I'd compare the NEX-7's focal speed to the Nikon D3200. My opinion is simply based on experience with both bodies and is purely subjective. In short, the NEX line, as a whole, attains focus very quickly. However, it is an advanced camera and does require a good dose of user input to get the most out of it.

The same is true of most high-end DSLRs. My $0.02...